SUBSURFACE CRETACEOUS AND PALEOGENE GEOLOGY OF THE COASTAL PLAIN OF GEORGIA by Howard Ross Cramer and Daniel Douglas Arden OPEN-FILE REPORT Slr--8 In cooperation with the U.S. Geological Survey Grant No. 14-080001-G-232 GEORGIA DEPARTMENT OF NATURAL RESOURCES ENVIRONMENTAL PROTECTION DIVISION GEORGIA GEOLOGIC SURVEY April 1980 L 0 SUBSURFACE CRETACEOUS AND PALEOGENE GEOLOGY OF THE COASTAL PLAIN ' OF GEORGIA by Howard Ross Cramer and Daniel Douglas Arden OPEN-FILE REPORT Str--8 In cooper!l~ir ii Jurassic Period ............................... 89 Early Cretaceous (Comanche) Epoch ............ 90 Late Cretaceous (Gulf) Epoch 93 Early Paleocene (Midway) Age 98 Late Paleocene and Early Eocene (Sabine) Ages . 101 Late Early and Middle Eocene (Claiborne) Ages 105 Late Eocene (Jackson) Age .................... 109 Oligocene Epoch .............................. 110 Neogene Period ................................ 116 WELL LOG ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 REFERENCES CITED 160 Appendix I Sources of information for this report 181 LIST OF TABLES Table 1. Well logs available for analysis ........ 124 Table 2. Tabulation of reflection coefficients greater than 0.1 ................... 125 LIST OF FIGURES Figure 1. Index map, Coastal Plain of Georgia, showing localities of wells................. 126 Figure 2. Basement (post-Triassic) surface configuration ....................... 127 Figure 3. Structures on the basement, Coastal Plain of Georgia .......................... 128 iii - Fi~u'l!'e 5. Figtrre 6. simple (JSOUgUer! 'g't"a~j:y:lln:ap Of Georg.ia al\d outline of.'~ ariti!as 6f a:e'!l'om~g~etic t::o,verage ........... ....................... . ....... i l3! 9 Chart: s:howing nornenc.lature used for preGu1fian C::retaceous I' ' coma:rrchean Seri~s .(and older?). ~o:Cks~ -bf the Geor~ia coa:s?taF l>l.h"in ........ .. -............... -~. lllO Structure-con-tour m-ap 1 top of the eomanchean. seri:es, <(:a:i\d,>O-l'der~) _..... 131 F-igu~e 8. ..\,,~ ._-'......,d..e.>.,u.-.u'~er '.) .. . . . . .. .. . ... . ,. ................ .,., .. .. . . :. 132 Titne-~rock ohart. of~ :ttle Gu.1f;ian:~:Gu-1.f'.i:an: -:Ser:ies ........................... ~ ....... ,.. ...... :. 1414 F:i:.g-tl~e 11. Til'neiM'l:'ock -n:ha.;rt . of: the'' Md:0wa;ranc: st~Jje 1 ~co:as:tal .'l?J.a:in- .of se:.o.;-g:ia ,. .................. - 1:~:3 6 Fig:tl!t'e -12. : S-tructut-e,..contour map 1 top.l>f :the ~MJ:dw.e.y.an stage I. oe&.11ltal Plain. of Georg-ia ............................ -............ ....... .............. -~ l3 7 FJ:ii~.re 13. x.sopa:ch ,m-ap~ M-idwa-yan: s.tage,. o~a:s;tal .P..la1. n o- f .G. aorg a. a ...... ~...... -.... -. ~. -...... .... . ~1/SB Fi9'~e 14. Time--r;ook-:rtt:nart of tf.he .-Sah'in:i:an: S:ta~e 1 ,..n -.: ~ -1 '..\I'0T;()..........,:~ r..:a.&... n .:..A., f . c...-~.v,~.-g-1 a . -........ ~ . .. . -.. .. .. - ... . . . .. .. . . . .. .,. :., Ui2 p-la:nkton.ic foranrih..i:f.er:: :zones,:: aild ~ ~:ea...-J.evel -chan9'es:~O'Q:o.rd:i.ng'1to nt&....,.,. ,. d l53 - :~-Tv'--'-0..- 'l. 1 .. -a:n s . . 'd- :.:r-1~~ : (l_,'::~J ..,..!f,) ....... ~...................... -.. . . . . : :F:i'~e: :29. ~ :rll'dexTYna.p, c~s?:~c't~s~ A: tO::. E 1 ... -,,.~.,.Q. c"~"'~':'St"-"al-: P-,t~..,&.~,1 -n- - .~ .~f--.-'G.~,.\,.:..,.I..'..;..L.~z:.,,.,a;.,a . ._.._.._._.._ ..,....,. ... , :l4 ~ -Fl~e :ao. :c:r~s: %ect.11!>n :A~AJ 1 ";Mu~cogeet :to .-: Se:rev.e n- 'CO.'I.ll'lt-.1:.:L~S , -.t,iQ~]'at>t':g. "J..a. "' ..... -......... ;., 1:i$ ,- F-i:~il"e ' :3-:1. 'C~&:.- %~'ori': -:s;..B,' ,.::.;sefu:i~o-:le ~unty I c:~EI'Dra:: :to t:~:~~m -~.o .[ 1 ~~ of'f~a. .. -.~.; .1~56 .F-i~:t-e' -3-2. - :c:.r:oss' 'tec:.t:-ii0n--c~t ~ :-a:.fid::. Dl-b:' ,'-:" .'l'~a~rt :"to :: 2B-t'O'bk.S 'C.O"U~~s r ~:ild: .Bibb :to :~ :Iir~hb'::ls~ coun:ti:es 1 -~G~'gia- " .... ...... ~~..... l ~"'57 :- F:!i:~e -3...3. ~:c:r.ms::~~tirori- -g>:..'E,' ~~ .m.~h'i:tin-.~co.untu, !"'""'""""'. .: 'l$9 T - J. -h..:.f t -\-:JcV.1~-:1..:a 1 0 co.,C... uShG-w ~ :t.he ' ~Ql01')~-ate :basin 1as does the structure-co-ntour map on the 'top Of ~the Sa;binilan Stage (Figure 16) The stru'Ctu:re..,.:contour mapcon the top of the Claibornian Stage (Figure ' lJ9) refl'e'~t>s :~c~J\t:i'tl'~<:fd :.~s-ettling ~f the basin after the C:ba.1/bo"%"1:ne, dd!uri-rtg ~tlhe L&.t:eE.IIDcceae. The thin Claiborne section in the ~entral Geot~gia tJpl.ff.t .iar=~a .aro\!lnd 'Coffee County may be Ute :r6s-ult cf '"'UPlift wh:t;oh .preee:t:~g:baCC~~s'bal fl])liain ww.as :.part -.:f 't:ne i:'Gul -.:coa$'t' contilftetl:t;:U '~&llt-dlf. JACKSONIAN STAGE Jackson rocks are well developed in Georgia and have been the subject of much study because they are part of an important water aquifer. They are Late Eocene in age. Because of their role in the ground-water resouces of the state, much is known about Jackson strata. Of special value are the works of Cooke and Shearer (1918), Herrick (1961), Carver (1966; 1972), Toulmin (1977), and Cushman (1935). Lithostratigraphy Updip, several different formations representing several different sedimentary environments are present. In the valley of Chattahoochee River, however, only the lowermost unit is well exposed. Toulmin and Lamoreaux (1963, p. 403) provide a good description. The Moodys Branch Formation is the basal unit of the Jacksonian Stage. On Chattachoochee River it rests unconformably upon the Lisbon Formation. The basal part of the Moodys Branch is well-indurated, very sandy, and glauconitic, fossiliferous, yellowish-orange limestone. Above the basal unit are very-coarse-grained sandstones and very fossiliferous, very sandy limestones. The contact of the Moodys Branch Formation with the overlying Ocala Limestone is not well exposed along Chattahoochee River; the state geological map (Pickering and others, 1976) does not distinguish the Moodys Branch Formation from the overlying Ocala Limestone. The Moodys Branch Formation has probably 'been overlapped by the Ocala Limestone. Eastward and northward from the exposures in the valley of Chattahoochee River, the -63- Moodys Branch cannot be distinguished from the overlying Ocala Limestone. The Ocala Limestone is a very widespread unit throughout the Coastal Plain and probably conformably overlies the Moodys Branch Formation. It is a very fossiliferous, micritic, relatively pure limestone; in many places it is a coquina of small fossils, largely bryozoans and fragments of other macr,ofossils. The dip of the Ocala is so gentle, and the formation so thick, that nowhere is a complete section exposed. Northward and eastward along the outcrop, the Ocala intertongues with clastic rocks; each of the tongues has a formal name. The state geological map recognizes the Twiggs Clay, the Irwinton Sand, the Sandersville Limestone, and others (Pickering and others, 1976). Carver (1966, 1972) and Huddlestun and others (1974; 1978) provide a summary of this complex. Downdip, the Jacksonian Stage retains its characteristics over a widespread area. It thickens toward the southwest, but because of its depth and undesirable water-quality it is not much sought after, and so little is known of it. The Jackson elsewhere is relatively thin, a few hundred feet at the most; this is due to post-Jackson uplift and erosion. The Jacksonian Stage in the subsurface is composed of two formations, a very widespread Ocala Limestone and a basal, more restricted, Clinchfield Sand. The Clinchfield Sand is described in detail by Herrick (197 2) . It is a basal sand a few tens of feet thick and is -64- correlateq with the Moodys Branch Formation. The Clinchfield becomes more calcareous downdip, and becomes indistinguishable from the overlying Ocala; it rests unconformably upon the Lisbon Formation . . The Ocala Limestone can be divided into two units. The upper unit thickens downdip and is not exposed in outcrop. It is white, recrystallized, somewhat sacchroidal, porous, very fossiliferous limestone. The lower part, everywhere present, is a cream colored, somewhat granular, much crystallized, sparsely glauconitic, fossiliferous limestone which is sandy at its base. Gypsum is found in the lower part of the Ocala in southwestern Georgia, but nothing has been published about the nature of this occurrence. The Ocala here is also dolomitized. Offshore, in the JOIDES corehole, Schlee (1977, p. FS) describes the Ocala Limestone-equivalent rocks as mainly packstone in the lower two thirds and grainstone in the upper one third. The rockis massive, dolomitic, hard to friable, fine- to coarse-grained, and contains scattered grains of glauconite. In the COST well, even farther offshore, the Upper Eocene rocks are fine grained, white to ta~ argillaceous, fossiliferous limestone. The top of the Jacksonian Stage is marked by a regional unconformity, in places manifest as a karst surface (Herrick, 1968). The basal Suwannee in some places is a very sandy limestone, and in others is a very dense dolomite with a distinctive signature on electric logs. The Ocala, like the -65- overlying Oligocene Suwannee Limesane, may be dOlowt.iz:ed',< and the. two may be difficult to distinguis.b.. The paLeontola.gical hiatus, between the two is very great, however. Biostratigraphy Biostratigraphically, the Jacksonian Stage is Late Eocene in age. In the COST well, the following indicat-e a Late Eocene age: foraminifers Globorotalia cerroazulensis Globigerina eocaena G. linaperta Nummu,li tes moodybranchensis Bulimina jacksonensis Cibicides yazooensis Siphonina danvillensis dinoflagellates Hornotryblium floripes Diphyes colligerum Areosphaeridium multicornu.tum Wetz~liella floripes Areoligera sp. Adnatosphaeridium sp. Polysphaeridium sp. Updip, the only planktonic foraminifers reported from Upperr Eocene rocks are Hantkenina alabamensis and G-l.oboro.ta:lia cerraazulensis cocoaensis. Huddlestun and others (1974, p . 2-3) include the< "Cooper M.:n:rl"', Twigg:s: Clay, Tivola Limestone, and- Cl.i:nchfi.e.Id San:d, all eqU'iv:alents: of the downdip Ocala Limestone~, n. the: Late Eacene P-16 and P-17 zones of the uppe-r part. of the' Jac!.kaoniarr S:.taql!'. (Figure 28) . Figure 21 is. a chart showing th.eo rrome:ncla.tture af the Jackson rocks- used in this repo.rt .. -66:.0 Structures All of the structures which are shown on the structurecontour map of the top of the Jacksonian Stage (Figure 22), have been impressed onto the surface by post-Oligocene tectonism. There are no structures which can be identified as Jackson, or post-Jackson-pre-Oligocene in age. It is evident, however, from the biostratigraphic hiatus between the Jackson and the overlying rocks, the clastic nature of the base of the Oligocene series, and the irregularity of thickness of the Jackson rocks as shown on the isopach map (Figure 23), that regional uplift and erosion did occur. The northeast-southwest trending belts of thick Jackson rocks alternating with thinner sections could be explained by faulting in which the thicker sections have been preserved on the downthrown sides during erosion. No physical evidence of the fault planes is present, however. The presence of the Southeast Georgia and the Appalachicola Embayments can be deduced from the isopach map because the Jackson rocks become thicker toward the basins. Details cannot be determined, however, because post-Jackson erosion has removed much of the upper part of the sections in southeastern Georgia, and the data are too sparse in southwestern Georgia. -67- OLIGOCENE SERIES To date, there have been no publications dealing exclusively with Oligocene rocks in Georgia, but the works of MacNeill (1944), Cooke (1923; 1935~ 1939), Herrick (1961), and Herrick and Vorhis (1963) contain much useful information. There is considerable uncertainty about the correlation of the various Oligocene units exposed in the Georgia Coastal Plain; the state geological map (Pickering and others, 1976) includ~ them as one unit, the Suwannee Limestone,but acknowledges the existence of other units. Lithostratigraphy The gentle dip of the Oligocene rocks prevents the exposure anywhere of the entire section despite the thinness of the various uniteS~ faulting and possibly gentle folding having produced structures which have compounded the confusion of the stratigraphic terminology. The M_arianna Limestone, according to Huddlestun and others (-1974 p. 2-10), crops out on Ocmulgee River in Houston County where it unconformably overlies the "Cooper Marl" of Late Eocene age. No description or thickness of the formation is given. This is the same exposure (called Byram Fo:rmatiom., unit B') descri-bed by Pickering (1970, p. 14) a:s massive, white to pale cream colored., plas.tic chalk interbedded with thn,, locally calc:i-ti-zed limestdne len.ses. The thlckne:ss .i:s :nc:>t giv.en, except that th~s unit and the one overlying it are 40 feet thick. Herrick a:nd others (19 6:8) c-orre.la:te this with the -68- Byram Formation from Mississippi. The Glendon Limestone overlies the Marianna in the same setting on the river (Huddlestun and others, 1974, p. 2-10), but no description of the lithology or thickness are given. This is the same exposure described by Pickering (1970, p. 14) which he calls the Byram Formation unit A. It is composed of alternating beds of chocolate-colored, sandy, calcareous clay interbedded with beds of white, hard, crystalline limestone. Herrick and others (1968) correlate these beds with the Byram Formation. These two formations are not known to crop out anywhere else in Georgia and are overlain by residual chert of the Suwannee Limestone. The Suwannee Limestone unconformably overlies the Glendon Limestone where the latter is present, and Upper Eocene rocks everywhere else. The Suwannee is a widespread, thin blanket of carbonate rocks in which outcrops are rare, but which typically vary from a friable mass of calcareous granules to hard, resonant limestone, everywhere very fossiliferous; it is generally yellowish or creamy in color. The surface expression of the Suwannee is generally red, clayey, fossiliferous cherty residuum which has been mapped as the Flint River Formation in earlier reports. Because of the gentle dip, complete exposures of the Suwannee are unknown, and the thickness has nowhere been determined from the surface. Drilling data indicate, howev~r, that the Suwannee is relatively thin, a few tens of feet in most places, but variable because of a profound unconformity -69- above it. The Chattahoochee Formation unconformably overlies the Suwannee Limestone in southwestern Georgia. The Chattahoochee is called the Tampa Limestone in some maps and is considered a facies of the same interval. The thickness of the Chattahoochee (or Tampa) Formation is about 100 feet according to Cooke (1943, p. 87), and includes a basal conglomerate composed of fragments of the underlying Suwannee (or Flint River) Formation and much sand. The limestones are dull and chalky, and contain considerable sand and clay in some places. Note that the Tampa Limestone, as identified in southwestern Georgia, is not the Tampa Limestone of eastern Georgia. The latter is clearly lithologically different and Hiddle Miocene in age. In the subsurface, the Marianna Limestone is from a single well in Grady County (GGS 962) where it lies below the Byram and is at least 292 feet thick; the well bottomed in this unit. The Marianna is very fossiliferous and is interbedded paleorange to cream, soft, granular limestone, cream colored marl, and thin beds of pale-brown dolostone and dolomitic limestone (Sever and Herrick, 1967, p. B52). The Byram Formation has been detected from one locality in the graben in a well in Grady County (GGS 962) (Sever and Herrick, 1967) where it underlies the Suwannee Limestone. The Byram here is 214 feet thick and is composed of yellowishbrown, dense, clayey, finely crystalline dolostone. It is considered to be Byram on the basis of its stratigraphic -70- position and because of similarities to the Byram beds which crop out in Florida (Sever and Herrick 1967, p. B50). The Suwannee Limestone is the most easily recognizable unit of the subsurface Oligocene rocks. It has two distinct subdivisions, according to Herrick and Vorhis (1963, p. 13). The upper part is light gray to cream or light brown, dense, nodular, cherty limestone which is often fossiliferous and somewhat sandy. The lower part consists predominantly of cream-colored relatively soft, somewhat chalky, fossiliferous limestone. At the base are rather dense, massive, sparingly fossiliferous limestones, and toward the northeast, this basal sequence contains sandy limestones. The thickness of the Suwannee se om exceeds 100 feet {Figure 25) because of an extensive and profound unconformity at th~ top~ The Suwannee Limestone rests unconformably upon the Ocala Limestone everywhere except in the southwestern part of the graben and in the outcrop on Ocmulgee River where it unconformably rests upon the Glendon or Byram Formations. The Chattahoochee Formation is the youngest Ol~gocene unit known from the Georgia Coastal Plain; it is also called the Tampa Limestone updip. These beds are sandy, dolomitic limestone, and clay and rest unconformably upon the Suwannee Limestone in southwestern Georgia. The thickness varies but is about 100 feet where the formation is completely present. Oligocene rocks which are on top of the Suwannee Limestone are present in the graben in Coffee County. They rest unconformably upon the Suwannee and contain a Late Oligocene fauna -71- (E. Applin 1960). These rocks are 150 feet thick, and are interbedded sand and shale, with some limestone (Applin and Applin, 1964, p. 90-91). A similar section is described by Herrick (unpublished) from Coffee County (GGS 1825) in which the rocks are logged as Oligocene undifferentiated and rest upon Suwannee Limestone. In the JOIDES core hole offshore, the thin (about 30 feet thick) Oligocene rocks are massive, faintly mottled, pale olive, clayey to silty, plastic, calcareous oozes. The grain sizes range from very fine to silt and clay; the coarsest detritus consists of foraminifer tests, glauconite, and scattered phosphate. There is no evidence of sorting or of a preferred arrangement of the larger fragments, and the total aspect of the sediment is that of a hemipelagic ooze that shows little or no evidence of reworking (Schlee, 1977, p. F7-F9) ~ the rocks are unnamed formally. In the COST well, still farther offshore, the upper 150 feet of Oligocene rocks are composed of shell fragments, claystone, and breccia with some clear to frosted, subangular to subrounded quartz grains. The lower 325 feet are largely white and tan limestone with some dolostone and chert interbedded. Some chalk and marl also occur near the base of the lower part. There is a marked unconformity at the top of the Oligocene Series in Georgia; this is responsible for the variable thickness of the Oligocene rocks. The contact of the Oligocene beds with the overlying Miocene strata is generally distinctive, as the Miocene rocks are largely clastic, although in some areas, -72- where they are carbonate also, the contact may be difficult to distinguish lithologically, so that paleontology is the chief means of distinction. Biostratigraphy Early. Oligocene Earliest Oligocene rocks are known from the JOIDES core hole, in which 30 feet of calcilutites, overlain by Early Miocene rocks, contain Pseudohasterigerina micra and Globorotalia postcretacea (Charm and others, 1969, p. D4). Early Oligocene rocks are also found at the base of the Oligocene section in the COST well. Here, cherty, chalky, dolomitic limestone contains Pseudohasterigerina micra and Cassigerinella chipolensis (Steinkraus, 1978). Middle Oligocene Middle Oligocene (sometimes called Vicksburgian) fossils have been found in the rocks offshore as well as in a few isolated localities onshore. In the COST well, the shell-fragment, claystone, and breccia unit at the top of the Oligocene Series, overlain by Middle Miocene rocks, contains Chiloguembelina cubensis, Globigerina ciperoensis, and G. ampliapertura, guides to Middle Oligocene strata. Onshore, Middle Oligocene rocks are c1lled .the Marianna and Glendon (or Byram) Formations. In an exposure on Ocmulgee River the rocks are included in the P-19 Zone by Huddlestun and others (1974, p. 2-3) (Figure 28), and a diverse fauna -73- cis present. It includes, according .to Herrick and ci:lihelr:B (.1968), eight types of megafossils and 79 species of micro- fossjjl.s which include: Clypeaster rogersi Paraster americanus Lepidocyclina mantelli L. undosa &Onion vicksburgense Discorbis arcuatocostata Valvulineria paucilocula Eponides advena Gyroidina vicksburgensis Pararotalia par va Planulina byramensis c'li'hes.e correlate with Middle Oligocene ronks elsewhere on the Gulf Coast, and particularly wi-th the Byram Limestone in M.i:s:sissippi. _Middle Oligocene rocks have also been identif.i-.ed in one well ~in Grady County (GGS 962) which Sever and Herrick (:19:67) correlate with the Marianna Limestone of Florida. In the .:rocks in Georgia, the following have been found: Robulus arcuato-striatus R. vicksburgensis Nodosaria latejugata N. ver.tebralis Globulina g~bba Guttelinaproblema Bul.I..m.I..na sculpt.I..ll.s Bolivina bl)ramensis Reuasella yramens.I..s Uv:iger.ina vickshJ.r g.ensis Ellpsonodosaria cf. ~- jackaonensis Discorbi s araucana Gyroidina v.1..cksburgensis Eponides byramensis E. advenus N:onion affine B1phonina advena Arromalin-a bilateralis Plarrulina mexicana Cibicidi~a americana C. mis-sissippiensis -74- Planktonic foraminifers are not reported, and are said to be scarce. Late Oligocene Late Oligocene (Chickasawhayan or Lower Chattian) rocks are widespread on the Georgia Coastal Plain and are the components of the Suwannee Limestone. The fossil lists of Herrick and Vorhis (1963, p. 16-18) do not include any planktonic foraminifers, so that biostratigraphic zonation based on these marvelous creatures cannot be established. Because this formation rests unconformably upon Middle Oligocene rocks it must be younger than Middle Oligocene, or Zone P-19 (Figure 28). Huddlestun and others (1974, p. 2-3) place this unit in the middle part of the Chattian, Zone P-21, although no criteria are listed. Oligocene rocks that overlie the Suwannee Limestone, and so must be late Late Oligocene (Upper Chattian) , are known from the Georgia Coastal Plain also. In southwestern Georgia, the Chattahoochee Formation and its calcareous ,equivalent, the Tampa Limestone, unconformably overlie the Suwannee Limestone. These rocks are late Late Oligocene (Huddlestun, in Weaver and Beck, 1977, p. 8) although no criteria are listed. These same rocks in Florida are in the P-22 Zone, late Late Oligocene (Huddlestun and others, 1974, p. 2-3) (Figure 28). Farther to the northeast, in the graben in Coffee County (GGS 509) , post-Suwannee rocks are present and described paleontologically by Applin and Applin (1964, p. 90-91). -75- They contain no planktonic foraminifers, but Miogypsina antillea,~ Gunteri, and Elphidium leonensis, which are Late Oligocene and Early Miocene guides, are present. E. Applin (1960) describes this material. Figure 24 is a chart showing the relationships and nomenclature of Oligocene rocks in the Georgia Coastal Plain. Structures Considerable evidence demonstrates the presence bf an erosion surface on top of , and in some instances within, the Oligocene Series. In most places at the top of the Oligocene Series there is a marked lithologic distinction between the Oligocene Series which is dominated by carbonate rocks and the overlying Miocene Series which is dominated by clastic rocks, in some places very coarse. In those places where the Miocene rocks are calcareous, paleontological distinctions are evident. The isopach map (Figure 25) shows the Oligocene Series in Georgia to be exceedingly thin except for the terrane within the graben, and absent in southeastern Georgia as a result of post-Oligocene erosion in the Peninsular Arch region. This is the "Orange Island" proposed by Vaughan (1910, p. 156). Broad belts of irregular thickness trending northeastsouthwest have been contoured. These are attributed to postOligocene erosion following faulting or possibly folding, with the thicker sections preserved on the downdropped blocks. -76- In Brooks County and vicinity, the structure-contour map shows that the Oligocene erosion-surface has been arched upward. This structure is post-Oligocene in age and has been described in detail by Weaver and Beck (1977) . In the COST well, Middle Miocene clastic rocks rest upon Middle Oligocene rocks, and in the JOIDES core hole, Miocene clastic rocks rest on Lower Oligocene rocks. The evidence for regional erosion within the Upper Oligocene rocks is partly lithological and partly paleontological. The uppermost Oligocene rocks, the Chattahoochee Formation and the post-Suwannee rocks within the graben unconformably overlie the Suwannee Limestone and are clastic at the base (Cooke, 1943, p. 87). These rocks also contain late Late Oligocene foraminifers (Huddlestun and others, 1974, p. 2-3) and Huddlestun (in Weaver and Beck, 1977, p. 8). Evidence for a broad regional uplift between Middle and Late Oligocene deposition stems from the distribution of the Middle Oligocene rocks. They are present below the Upper Oligocene rocks only in the graben and in one isolated area along Ocumlgee River (Herrick and others, 1968~ Pickering, 1970). They have been preserved in downdropped blocks of faults, while the rest of the rocks were removed by post-Middle Oligocene uplift before the Upper Oligocene Suwannee Limestone was deposited. The identification of Oligocene and post-Oligocene faulting comes from the evaluation of several factors, some more obvious than others. Faulting here is difficult to -77- establish by physical criteria alone, such as fault-plane features, because no faults are known to have been intersected by any of the wells. The faulting shown on the isopach and structure-contour maps (Figures 25 and 26) (except that which is specifically described otherwise) is post-Oligocene and pre-Miocene in age; some may have occurred during the Oligocene and some may have occurred during the Miocene. The erosion surface on the top of the Oligocene rocks has an unknown relief. It could be very great because of presumable karst development, although none is surely known except from one locality (Herrick, 1968) . In several localities, however, where wells are closely spaced, faulting is a surer explanation for the difference in elevation of the Oligocene erosion surface. Such examples would be the faults in southern Brooks County and in Glynn County. In those instances where the faulting occurred before the development of the erosion surface, the evidence for the faulting comes from interpretations of the isopach map (Figure 26); thicker Oligocene sections are preserved on the downdropped blocks. Examples of these are the faults in Dodge and Coffee Counties. Zoback and others (1978) illustrate similar evidence for Oligocene faulting from South Carolina. In some instances the evidence for the faulting does not come from the Oligocene rocks themselves, but rather comes from the offsetting of the underlying beds. Examples of this are the faults in Toombs, Coffee, and Screven Counties. There is some faulting which has been identified as -78- Oligocene-related even though Oligocene rocks are not involved. For instance, the faults which intersect the Fall Line are considered post-Oligocene although only some of them intersect Oligocene rocks; they are considered to be part of the same tectonic episode. The orientation of the faults is difficult to establish. The orientation of those which intersect the Fall Line are interpreted from geomorphological expression, i.e., the fault traces are along the river valleys. Offset outcrop patterns along the Fall Line also allow for the orientation of some of the faults. The f~ult trending roughly north-south in Glynn County and vicinity parallels other faults in Glynn County which, because of scale, are not shown. Gregg and Zimmerman (1974, p. 15, pl. 2) show these smaller, similarly oriented faults based upon more closely spaced data. In general, most of the faults have orientations which would be amenable to those expected from the tectonic hypothesis which encourages a northeast-southwest linear orientation for structures, i.e., a trailing margin of continental segments of plates moving northwestward (Batt, 1979). One fold, or arch has been identified. Structure contours on the Jacksonian and Claibornian Stages (Figures 20,23) and cross sections B and E (Figures 31, 33) east of the present coastline indicate that a fold is present. The age of this feature is uncertain, but because Oligocene rocks at the crest of the feature are absent or thin (Figure 25), it is probably post-Oligocene in origin. Its relation to Miocene rocks is -79- unknown. It may be a part of the tectonism which was associated with the Peninsular Arch at the end -of the Oligocene. . Schlee. (1977) describes this feature in detail. A graben, or a zone of complex structures collectively resulting in a ~raben configuration, trending diagonally northeast-southwest across the Coastal Plain, is the most pronounced structural feature present on the maps. This feature.' was first suspected by Owen (1963, p. 24) who calls attention to a structural anomaly in Mitchell County which l'lle identiies as a11 syncline or downfaul ted belt 11 This same, feature is recognized by Herrick and Vorhis (1963, p. 55) who provided the name Gulf Trough of Georgia for it but made no intexpretation of its origin. Callahan (1964, p. 23) notes this feature with its present dimensions; he interpreted it as two parallel,. down-to-the-sea normal faults. Patterson and Herrick (1971) question its existence. A synthesis of the data, both local and regional., support the concept of a singular structure trending northeast-southwest which has had a marked influence on the geology of the Coastal Plain. The evidence for this graben structure (and other Oligocene faulting in Georgia) is outlined in Cramer and Arden (1978) and is given here in detail. The name Gulf Trough is used for t:his fea-ture at the suggestion. of Hendry and Sproul (1966, p. 97) whc:;J mote that i1t pas-ses into Florida also. Gelbaum (1979) provides much hydrologica-l and lithological det.ail. The :f'ault boundaries of the trough can be disting:ui.she:d -80- in some places. The wells in Toombs County (GGS 95, 146) are but a few miles apart, yet show the tops of all of the underlying units to be offset by several hundred feet, with the south side down. The tops of the Oligocene rocks are also offset, suggesting that this particular part of the fault system occurred, in part at least, after the post-Suwannee erosion surface had developed. ~he faulting in Coffee County (GGS 445, 446) is in a similar setting: the tops of the pre-Oligocene units to the south are offset by several hundred feet when compared to the tops of those to the north, and the thickness of the Oligocene rocks on the south block is greater than the thickness of those on the north block. The top of the Oligocene rocks on each block, however, is not appreciably different, suggesting that this faulting preceded the formation of the erosion surface. Toward the southwest, the tops of the Oligocene rocks within the trough are structurally lower than the tops of the Oligocene rocks outside the trough (Figure 25), but the spacing of the wells is such that the evidence for faulting is not as dramatic as those elsewhere, and the wells are not deep enough to reveal offsetting on lower units, if present. Furthermore, the isopach map of the Oligocene Series (Figure 26) shows that the Oligocene rocks within the trough are thicker than those outside it. Pre-erosion faulting, with the troughside down, would explain this. There is evidence for faulting within the trough. The wells within the polygonal block in Coffee County -81- (GGS 468, 508, and 509) reveal an abnormally thick Oligocene section when compared with those outside of the block (GGS 446, 447, 448). No appreciable offsetting of the Oligocene erosion surface is evident, suggesting that this faulting preceded the post-Oligocene erosion. This same interpretation applies to the fault block containing GGS 1825 in Coffee County. The southermost fault in Candler County, within the trough, is also revealed by distinct offsetting of the Oligocene surface (GGS 740, 963); the wells are not deep enough, however, to provide any data about the Oligocene isopach values. Evidence for deformation of the rocks within the trough can be seen on the structure-contour map of the Oligocene Series (Figure 25) in which a distinct structural high can be seen in Colquitt County. The faulting affects the postOligocene erosion-surface, and may be Neogene in age. Unpublished information about Oligocene and younger rocks in the trough, gleaned from numerous wells, indicates that the Oligocene rocks have been involved in crustal activity, and that the amount of heave on the faults in general becomes less toward the northeast. The other characteristics which show the presence and influence of the Gulf Trough include interpretations from piezometric maps of the Georgia Coastal Plain, such as that in Callahan (1964, pl. 1 and later versions). A pronounced change in the piezometric gradient is shown, with a linear trend in the geographic position of the Gulf Trough toward the northeast from Coffee County. Such a trend may be the -82- result of changes in permeability or lithology. The map showing the location of epicenters of historical earthquakes in Georgia (Lance and others, 1977) indicates that two of the six known localities are in the Gulf Trough. Gelbaum (1978) indicates that water quality within the confines of the Gulf Trough in southwestern Georgia is distinctly different from the water quality of the rocks outside. Gelbaum also provides a detailed summary and review of the characteristics of the Gulf Trough. Clearly there is a geological reason for the difference. Further evidence for the existence of the Gulf Trough as a structural feature comes from the overlying rocks. Weaver and Beck (1977) have provided a detailed analysis of the Miocene rocks, and they show that Miocene beds in the area of the trough are abnormally thick also. Gelbaum (1978) shows that there is over 700 feet of Miocene rocks in the trough in Colquitt County. These data suggest that the tectonic activity of the Gulf Trough continued into the Miocene Epoch. Finally, a structural interpretation which includes the Gulf Trough best explains the distribution of Oligocene rocks on the Georgia Coastal Plain. Upper Oligocene rocks rest on Middle Oligocene rocks within the trough, whereas Upper Oligocene rocks rest upon Upper Eocene rocks almost everywhere else. Figure 27 is a schematic illustration of this explanation. Transgression of Oligocene seas began during the Early Oligocene and covered the present Coastal Plain during the Middle Oligocene. Following Middle Oligocene transgression, -83- faulting preceded erosion; Middle Oligocene rocks were removed from the Coastal Plain except in the Gulf Trough where they were preserved on the downdropped block and in at least one isolated area now exposed on Ocmulgee River. Following the erosion, a second, Late Oligocene transgression took place, depositing Upper Oligocene rocks on the recently exposed Upper Eocene surface and on the Middle Oligocene rocks in the trough. Erosion following the deposition of the Suwannee Limestone resulted in its almost complete removal from everywhere except in the trough where continued downfaulting preserved a thicker section. Following this second transgression and erosion, a third transgression developed, and the Upper Oligocene Chattahoochee Formation and equivalents were deposited on top of the eroded Suwannee Limestone. Miocene uplift and erosion removed much of the Chattahoochee Formation but because of continued graben development of the trough, these rocks are preserved there also. -84- NEOGENE SYSTEM ~he Neogene System on the Coastal Plain of Georgia is represented by rocks of Miocene, possibly Pliocene, and Pleistocene age. The details of these rocks are not included with this report because: (1) the definitive report of Weaver and Beck (1977) includes most of the current information about them; (2) their potential as petroleum reservoir or source rocks in Georgia is exceedingly low, and (3) stratigraphic studies being undertaken at the present time on the Pliocene and Pleistocene rocks would make any analysis of the older data in this report outdated. The reader is referred to the reports of Weaver and Beck (1977) and of Her~ick (1965) for information about these rocks. All of the Neogene rocks in this report are shown on the cross sections as Nu, "Neogene, undifferentiated." -85- GEOLOGICAL HISTORY The basement Paleozoic rocks of various ages and types form the foundation upon which large tension faults occurred which appear to be related to the opening of the Gulf of Mexico (Pilgei, 1978) and to the opening of the Atlantic Ocean during the early part of the Mesozoic Era. The faulting produced grabens in what are now the basement rocks of the Gulf and Atlantic Coastal Plains of North America, including Georgia. The grabens were filled with sediments, presumably Triassic and possibly Jurassic onshore, and which include much arkose, conglomerate, and shale. These sedimentary rocks were invaded by basic rocks, in the form of sills, flows, and dikes. Similar arkose-filled, diabase-invaded grabens occur in surface exposures to the north of Georgia along the east coast (McKee and others, 1959). The distribution of the basement rocks and a discussion of their geological history is beyond the scope of this report, but Gehrt and others (1978a) provide a review. Following the Triassic graben-filling episode and igneous intrusion, erosion commenced. If the rocks below the unconformity are Paleozoic and Triassic and the overlying rocks are possibly Upper Jurassic (Gray, 1978} or certainly Lower Cretaceous offshore and probably Lower Cretaceous onshore, then the time of the development of the unconformity can be documented. It is these -86- post-Triassic events and features which shape the foundation for the purpose of this report--the identification of a stratigraphic framework to which offshore seismic surveys may be related. Following the post-Triassic erosion, a distinctly different sedimentation regime was inaugurated, and the rocks and structure of what we know as the Coastal Plain were formed. Depositional sequences Early in the history of the studies of the Georgia Coastal Plain, but especially since the work of Veatch and Stephenson (1911), geologists have recognized that the rocks can be divided into sequences of strata bounded by substantial unconformities, paleontologically identifiable, and correlated grossly with the various subdivisions of Cretaceous and Cenozoic rocks elsewhere on the Gulf and Atlantic coasts. In the late 1960's, information about subsea rocks offshore, regional oceanic unconformities, and submarine deformation began to accumulate as a result of marine seismic investigations. During this same period, micropaleontology became important as the correlation potential of planktonic organisms was fully appreciated. The Foraminiferida-based biozonal concept of time-rock subdivision espoused by Bolli (1959) was first applied to the rocks of the Gulf Coastal Plain (including those of Georgia by inference), by Berggren (1965), and the rock-stratigraphic subdivisions of Georgia were placed in an international setting. Following the ability to identify strata with great precision in the subsea by seismic characters, geologists -87- have been able to recognize packages of sediments representing cycles of marine transgression and regression. A depositional cycle has been defined by Mitchum and others (1977, p. 53) as: a stratigraphic unit composed of a relatively conformable succession of genetically related strata and bounded at its top and base by unconformities or their correlative conformities. They describe various scales of depositional cycles. Some are large scale, such as the mutiperiod, cratonic sequences of Sloss (1963), and some represent much smaller intervals of time and space which are from smaller sea-level fluctuations and which may be in response to global eustatic changes of level or to local tectonism. The recognition of such cycles, coupled with the precision of dating based upon planktonic organisms, has let to the identification of cycles of marine transgression and regression on the Georgia Coa~tal Plain. These transgressions and regressions have resulted in the unconformities which bound the wellknown units of Cretaceous and Cenozoic rocks that had been recognized earlier from surface studies. It is these unconformity-bound sequences, here called stages, that are the subdivisions of time and rocks used in this report. At about the same time, Vail and others (1977) recognized, on the basis of international studies utilizing seismic stratigraphic techniques coupled with other stratigraphic tools, global unconformities, cxplQined for the most purl by sea-level changes. The chart showing the relative sea level -88- stands during the Cretaceous and Cenozoic is given here as Figure 28. Jurassic Period No Jurassic rocks are reported from the COST well offshore Georgia. There, Lower Cretaceous rocks rest upon Paleozoic rocks. The southwestern part of Georgia, following the erosion of Triassic rocks, experienced renewed unrest in the form of continued foundering of the graben areas. This would have been in response to continued tension resulting from the northwe5tward drift of the North American plate (Bott, 1979). Wit~ this foundering, sedimentation began in the low areas and: spread northeastward, and the Appalachicola Embayment appeared. Sedimentary rocks of Jurassic age are documented from nearby Florida (Appegate and others, 1978) and it is possible that the transgression brought conditions for similar rocks to have been deposited in Georgia (Gray, 1978). If so, these rocks are included in this report and maps with those described as Comanchean (and older?). The lowermost Comanchean (and older?) rocks which may be Jurassic, contain a succession of conglomeratic red sandstones and arkoses which thin to a feather edge toward the north in Dougherty County (GGS 108) and toward the east in Echols County (GGS 189). The coarser detritus in on the northern side of the embayment, suggesting that provenance was primarily from that direction, and the presence of feldspar in the section -89- indicates a proximity to the source area. The conglomerat.e is composed of clasts of a variety of rock types, reflecting considerable relief on the erosion surface during the time of deposition. No fossils are known from these rocks in Georgia. They are presumed to be possibly Jurassic on the basis of their stratigraphic position alone. They lie unconformably above the graben-filling, diabase-intruded Triassic rocks, and are below similarly unfossiliferous rocks considered to be Early Cretaceous in age. Whatever the age of these rocks, they demonstrate post Triassic transgression upon the continent. Early Cretaceous (Comanche) Epoch On the Atlantic side, Lower Cretaceous (Comanche) rocks are present in the COST well. The sequence of sediments, from a basal conglomerate zone 300 feet thick, overlain by clastic rocks which are predominantly red beds, sandstone, and shale and which contain minor amounts of anhydrite, coal, and dolomite, and with the upper part of the section dominated by anqydritic limestone and dolomite, is that which would be expected from overlap in graben- or rift-filling sedimentation during the early breakup of a crust, according to the model of Emery (1977). According to Lachance and Steinkraus (1978, p. 49), the Aptian portion of the Lower Cretaceous section in the COST well contains a few crinoid stems, ostracodes, pelecypods, gastra.pods, and a specimen of the foraminifer genus Hormosima. -90- Sparse dinoflagellate assemblages occur in rocks between 7500 and 8720 feet, and a good assemblage between 8720 and 8900 feet. A terrestrial to marginal marine environment is suggested, with a shallow marine transgression being reflected by the dinoflagellate-bearing rocks. In the Albian portion of the Lower Cretaceous, some marginal marine but predominantly inner shelf environment deposition (0-50) feet is present between 5950 and 7500 feet in the well. Poor arenaceous foraminiferal assemblages persist downward to 6190 feet; a few non-diagnostic ostracodes occur in the samples. Somewhat diverse assemblages of spores and pollen are present throughout, and dinoflagellates, less common, are present in most of the sidewall cores. Nannofossils include species of Braarudosphaera and Nannoconus. Once sedimentation began in that setting, terrestrial rocks were deposited first and as time progressed, marginal sediment~ were deposited; overlap is suggested by this sequence and also from the interpretations of seismic stratigraphic sections offshore (Buffler and others, 1979, Figure 7). Whether the overlap proceeded as far as the present-day coastline or not ~annot be determined, as no Lower Cretaceous rocks are present onshore on the Atlantic side; her~ Late Cenomanian or Turonian sediments rest upon the basement rocks. Post Comanchee erosion removed whatever rocks may have been present. A fault has been postulated, with the onshore side upthrown (Figures 7, 31, and 33) to account for the presence of such a thick section of Early Cretaceous-aged rocks adjacent to an -91- area where none is present. rhe thick section was pres-erved on the downdropped block. In the Appalachicola Embayment, Lower Cretaceous rocks are widespread and thick, Jurassic and Lower Cretaceous rocks are documented from Florida and Alabama, so that their overlap as far inland as Georgia is not to be unexpected as the downwarp of the Appalachicola Embayment continued. These rocks , are largely unfossiliferous red shale and sandstone and are interpreted as the basal clastic rocks filling the low areas on the foandering basement and forming the Appalachicola Embayment. Whether Comanchean seas transgressed farther inland than the present rocks show, cannot be determined, as no outcrops are known in Georgia. Whether the Comanchean seas from the Gulf fused with the Comanchean seas from the Atlantic is not known either~ as the present rocks are not connected. Babcock (1969, p. 25), and Toulmin (1955, p. 210) show Comanchean rocks absent on the crest of the Peninsular Arch in north Florida and south Georgia. Applin and Applin (1965, p. 4) show that the Comanchean rocks include a basal clastic unit which transgresses onto the Peninsular Arch from the south, and Jordan and others, (1949, sees. B, C, and D) show that the basal Comanchean beds ib southern Georgia are clastic and lie upon the eroded surface of Paleozoic rocks on the Peninsular Arch. Following Comanche deposition, the sea withdrew and erosion occurred. The presence of lignite at the top of the Comanchean (and older?) Series, the irregular thickness distribution of the Comanche beds and their complete removal in -92- places, and the basal clastic formations of the base of the overlying Gulfian Series belie this sequence of events. No Comanche rocks are present on the Atlantic side; they were removed during this episode if they were ever present. The Yamacraw Ridge (Figure 3) may have formed at this time also. The withdrawal of the sea following the deposition of Comanche rocks corresponds to the cycle of sea-level fall recognized by Van Hinte (in Vail and others, 1977, p. 85) (Figure 28). This event may actually have taken place during the Eqrly Cenomanian, as Upper Cenomanian rocks rest upon Comanche rocks in Georgia. The post-Comanchean sea-level fall can be identified globally (Vail and others, 1977, p. 93) when the sea was at a lowstand. The stratigraphic and structural relationships of the Comanchean Series above and below are shown on cross sections A-F (Figures 29 to 34). Late Cretaceous (Gulf) Epoch Following Comanche uplift and erosion, there was a transgression of Gulfian seas. A basal clastic formation, the Atkinson, was deposited in southern Georgia and Florida. It passes northward, via facies changes, into the more terrestrial Tuscaloosa Formation (Appl~n and Applin, 1947). The Tuscaloosa is Cenomanian (Stephenson, 1942, chart 9) and the Atkinson contains Late Cenomanian ostracodes and Foraminiferida. The upper portion of the Atkinson is absent over large parts of thePeninsular Arch in nearby Florida, and the lower portion -93- is thin or absent in the same region (Babcock, 1969; Applin and Applin, 1967, pl. 3). This suggests that the basal Atkinson Formation lay across the Peninsular Arch, and that there was post-Cenomanian deformation and/or uplift of the Peninsular Arch, and the area to the east, at least as far east as the COST well, where no Cenomanian rocks are present. Gohn and others (1978b) note a larger hiatus within the Gulfian Series of South Carolina in which rocks of Turonian and Coniacian ages are not presenb this hiatus, while not identified biostratigraphically in Georgia, may be correlated in part with the erosion surface on the top of the Atkinson and Tuscaloosa Formations. Such an hiatus is shown by Stephenson (1942, chart 9) in the outcrop along Chattahoochee River. Following the erosion of the Atkinson and Tuscaloosa Formations, the sea again transgressed onto the continent. Offshore, in the COST well, the basal sandstone of the Gulfian Series, probably Cenomanian, lies on Comanche rocks. According to Lachance and Steinkraus (1978, p. 49) the lowermost Upper Cretaceous rocks in the COST well, sandstone (which they call Cenomanian) are from a middle to inner shelf environment (0-300 feet). They do not cite the basis of the judgement. Above the basal sandstone lies progressively finer clastic material and increasing amounts of carbonates of Turonian, Coniacian, Santonian, Campanian, and Maastrichtian ages. Clearlv, overlap onto the continent is indicated. These rocks were deposited in an outer shelf environment, from 300-600 feet d~ep according to Lachance and Steinkraus (1978, p. 48). -94- Onshore, the basal clastic unit was deposited on the post-Atkinson erosion surface. It is noted in Florida as the LaCrosse Sandstone (Babcock, 1969) and lies upon Paleozoic rocks on the Peninsular Arch where the Atkinson and Lower Cretaceous rocks if present, were removed. It lies upon the lower member of the Atkinson where the upper member was removed, and in some places it lies upon the upper member. In Georgia the basal beds of Austin age are clastic, and even conglomeratic in places, and a persistent sand formation overlying the Tuscaloosa is logged as Eutaw (restricted) (Herrick 1961; Herrick and Vorhis, 1963). This is a fineto medium-grained, phosphatic, glauconitic, shelly, somewhat indurated sandstone and is the basal sandstone of the unit overlying the post-Tuscaloosa erosion surface. It crops out along Chattahoochee River also. Overlying the basal clastic unit everywhere is a sequence of marine rocks which are predominantly calcareous clay and shale, w:ith intercalated calcareous sandstones. At the top of the sequence in southeastern Georgia the rocks are predominantly carbonate with evaporite; this is the Lawson Limestone of Maastrichtian age. Toward the Fall Line, these calcareous shales become intercalated with discrete sandstone formations which crop out along Chattahoochee River and the Fall Line. Toward the northeast the section becomes almost entirely sandstone and the individual formations cannot be distinguished. In the outcrop area, unconformities are noted within the intercalated sandstone and shale formations along Chattahoochee -95- River (Stephenson, 1942, chart 9), rro doubt refl-ecting ~a fluctuating strandline throughout Gulf time. ~ Biostr.atigraphi~c .contrci.l of the unconformities downdip has not been :establ-ished except in the COST well, and all of the post-Tuscaloosa rocks above the basal sandstone are very similar. The loc:ation of most of the unconformities, if present downdip, cannot ne established at this time. It is possible that the updip alternations of the rocks rn.ay be due to climatic or to tectonic events which resulted .in :the lthologic changes. Berry (1917) identif.ies an Upper :cretac,eous deltaic sequence in the northeastern hla:bama Coastal Plain :considered to be the Tuscaloosa Formation, tongues of which may extend into Georgia. Hester (.1968) described the deltaic character of the Cusseta Sand. ~The continued existence of the Appalachicola Embayment can be identified from the isopach pattern of Gulf rocks (Figure 10). In the western Coastal Plain, Gulf rocks are thickest. The thickness has been ascribed to a depocenter, but it is :possible that it is a structural and erosional phenomenon. Post-Cretaceous faulting, in which this area was downdropped and the surrounding areas uplifted, would have res.lil.t.ed in these :being preserved from ,erosion. Not enough evidence is present to identify-the ,exiostence of the Southeast Georgia Embayment during Gulf time. The rocks -thicken seaward, but whether a ::structure ,:em:bayment was present cannot be determined from onshore information. Seismi-c .lines shown by Buffler arid others (l-979, Tigure 7) -96- indicate transgression across a broad shelf. An event which resulted in the uplift, possible deformation, and removal of some of the Atkinson Formation of Cenomanian age has already been described. Other tectonic events occurred, either during or after Gulf deposition. The Echols High in southern Georgia is a Late Cretaceous feature. .Here Gulf rocks are very thin, and this is attributed to post-Gulfian uplift and erosion. Applin and Applin (1967, p. G30) indicate that the event occurred during the Gulfian Epoch and resulted in a barrier which influenced sedimentation on both sides. Whether this feature is a result of folding or faulting cannot be determined from the data in Georgia. Faulting with a trend subparallel to that of the Echols High occurred at a later time (following Sabine deposition) and earlier (Winston, 1976b, p. 43). The Middle Ground Arch (Winston, 197Gb. p. 42) is also parallel with the Echols High and may be an expression of the same tectonism. Faulting has been used to explain the anomalously thin section of Gulf rocks in Glynn County (GGS 1197) , and unpublished seismic data indicate that other faults are present within the Upper Cretaceous terrane in Glynn County. Following or contemporaneous with the faulting and the formation of the Echols High, the sea regressed again, and the Cretaceous rocks were eroded. Nowhere are latest Maastrichtian rocks present in Georgia or in nearby coastal states (Hazel and others 1977, Figure 3). The CretaceousPaleogene boundary is everywhere marked by an erosion surface. -97- r Figure' 28 shows this erosion surface due in part also to post-Cretaceous sea-level fall. (Vail and others, 1977) Early Paleocene (Midway) Age No Midway (Danian) rocks are present in the COST well nor in any of the wells onshore on the Atlantic side. Rocks deposited during the Midwayan Age are confined to one area on the Coastal Plain which is bounded to the south and east by faults and to the north by outcrops. The orig.inal nature and extent of Midway rocks in Georgia is unknown, although some inferences can be drawn about their character and distribution. The Clayton Limestone, sandy at its base, is a marine deposit which rests unconformably upon Upper Cretaceous rocks. A regional unconformity occurs at its top so that its original extent and thickness are unknown. Toward the south and west, in Florida and Alabama, Midway rocks are more extensive and thicker. Toward the north and east, clay interbedded in the limestone suggests that a clastic facies occurred in that direction. Isolated remnants of Midway rocks, probably preserved in downfaulted areas, are present in Twiggs County (Figures 12 and 13). These are estuarine in character (Tschudy and Patterson 1975) which would not be unexpected in that area if transgression . were from the southwest. Midway (Danian) rocks are also present in South Carolina (Hazel and others, 1977) (Gohn and others, 1978b). Toward the south in Georgia, the Clayton Limestone becomes very sandy, and in one place is entirely sandstone -98- (Early County, GGS 437). This indicates that the Echols High was the provenance for the Clayton sand, and that Midway seas may never have been present in the southern part of Georgia. These criteria, including a basal sandy limestone, the thicker, more widespread Midway rocks in Alabama, the estuarine facies along the Fall Line, shallow marine exposures in South Carolina (Gohn and others, 1977 p. 70; 1978 b), and the sandy facies of the Midway toward the south, indicate a marin~ transgression onto the Georgia Coastal Plain probably from the southwest. Whether the Echols High terrane was an isolated island feature in the Appalachicola Embayment or the northern edge of an extensive landmass which includes most of what is now Florida is unclear, although most of nearby Florida has Sabine rocks overlying Cretaceous rocks, indicating post-Midway erosion. Following Midway deposition, uplift of the region resulted in the erosion and removal of most of the Midway rocks in Georgia. The uplift was accompanied by faulting which has allowed the preservation of Midway strata on the downdropped blocks. The underlying Gulfian Series are thickest here where they are overlain by Midway strata (Figure 10) as they were preserved from post-Midway erosion. While the orientation of the faults cannot be determined with precision because of the lack of data, some regional patterns are evident. The northeast-southwest tranding faults are compatible with others on the Coastal Plain, -99- i. to be expected as a response to theLtectonic forces resul ticng from:the northwestward drift of a passive continental margin (Bott , 19 79 ) . The prominent fault trending northwest-southeast at the eastern edge of the Midway terrane (Figures 12 and 13) is significant. This is also the western boundary of the Centr-al Georgia Uplift, and is more or less parallel w:Lth the Peninsular Arch, a feature which had been positive before Mitructure-contour maps of many of the other Coastal Plain units, indicating a continuous effect on the structure and sedimentation after Midway time. Cross section A-A' (Figure 30), shows this positive area. i~ Note that the Upper Cretaceous rocks east of this fault (Figure 1.0) are thin, indicating further erosion of the Cretaceous terrane after Midway rocks had . been: removed; in CO~fee County, no Upper Paleocene rocks are present either, suggesting that that area was positive ev:en ater Midwp.y uplift and erosion. It was not covered by .-marine tran~gressions . until Early Eocene time. r The events at the end of the Midway which re..s.u:J:ted. in or -were accompanied by sea regression, correspond to the rapid fall in sea level at the end of the Daniran (Figure ' 28) (Vail and others, 1977, p. 87). This ,falLin ' tSea .level appears to have been global in nature (Vail and others, 1977, -100- p. 93), and the unconformity at the top of the Midway rocks represents this particular low stand. Late Paleocene and Early Eocene (Sabine) Ages Sabine transgression is shown by clastic, calcareous marine rocks of Late Paleocene age resting upon Maastrichtian rocks in the COST well, and by calcareous, clastic rocks of Middle Paleocene age, overlain by rocks of Late Paleocene age, resting upon Maastrichtian rocks in southern Geo~gia and the Echols High terrane. The Late Paleocene rocks in the COST well area are in prograding clinoforms (Shipley and others, 1978) indicating that this area was the seaward edge of the depositional sequence at that time. According to Lachance and Steinkraus (1978, p. 48), the Sabinian Stage here was deposited in water 300-600 feet deep on the outer shelf, as shown by the presence of the benthonic foraminifers Cibicides compressa Dorothia bulleta Eponides bollii Marssonella identata Spiroplectammina trinitatensis Carbonate rocks, and some evaporites overlie the basal clastic rocks, indicating further sea-level rise and marine transgression onto the Georgia Coastal Plain. The evaporites increase southward toward Florida in the Cedar Keys Formation (Chen, 1965, p. 42-43) and are the result of shallow seas with restricted circulation. Nowhere is halite present, however, suggesting that the evaporite cycle was never carried to completion during any of the fluctuations. Northward into -101- Georgia and seaward toward the Atlantic, the evaporite becomes less common and normal marine limestones and calcareous shales predominate. The landward extent of the transgression is unknown because of post-Sabine erosion, but the section of carbonates over 1000 feet thick in Wayne and Pierce Counties suggest that it was very extensive. Toward the Fall Line Sabine rocks are predominantly terrestrial in origin and contain bauxite and kaolin. These are overlain by very thin marine sandstones and a pronounced unconformity. The absence of Upper Paleocene rocks within the Sabinian Stage in the Coffee County region indicates that this area may have been a highland during the early part of the Sabine transgression and that it was not fully inundated until Early Eocene time. Whether this area was an island or a peninsula attached to the mainland to the north is not known. This sequence of deeply eroded, once-thick rocks conforms to the model proposed by Vail and others (1977, p. 92) in which one of the highest stands of sea level, globally,was during the Sabinian (Figure 28). Post-Sabine uplift and erosion is demonstrated paleontolog.ically, lithologically, and geometrically. A substantial paleontological hiatus is present between Sabine rocks and those of the overlying Claibornian Stage. Middle Eocene rocks rest with profound unconformity upon lowermost Eocene rocks in the outcrop area, and upper Lower Eocene rocks rest upon Upper Paleocene rocks in the COST well. -102- The overlying Claibornian Stage contains a basal clastic unit (the Tallahatta Sandstone, or , where overlapped, Lisbon Formation) which is everywhere present above the Sabine rocks, reflecting Claiborne transgression over the eroded Sabine surface. The uppermost Sabine rocks in many places contain evidence of weathering, such as limonitization, leaching, bauxitization, lignite, etc. The very th~n (90 feet) Sabine section in the COST well is not due to post-Sabine uplift and erosion, because Shipley and others (1978) show that there is no appreciable deformation within the Cenozoic rocks in the vicinity of the COST well and that there are prograding clinoforms representing lower Cenozoic sedimentation. These shelf-edge deposits indicate a substantial transgression upon the continent during the Late Paleocene Age. Such overlap was very extensive, globally, as shown by the model of Vail and others (1977) (Figure 28). The most pronounced feature of Sabine tectonism is faulting; this has been deduced from the geometry of the Sabine rocks and the fall in sea level. A prominent fault, trending northeast-southwest is present in southern Georgia. The southern block is downdropped at least several hundred feet and a thick carbonate section was preserved from postSabinian erosion, whereas a similar thick carbonate section which was present to the north of the fault on the upthrown block was removed by erosion. This is shown on the cross sections C and D (Figure 32) and on Figure 15. -103- Faults similar to this in magnitude and orientation may be interpreted from the work of Chen (1965, Figures 24 and 25) when considered in conjunction with the work of Applin and Applin (1967; pl. 2, Figure B) and Winston (1976b, p ,. 43, Figures 2 and 3). Here sharp facies changes accompanied 'by distinct isopach patterns are present in an area on the Peninsular Arch characterized by ridges which cross the aJ:~ch., (producing high and low areas) and which are parallel to the proposed fault in Georgia. I this is the correct explanation, then the Suwannee Saddle of earlier authors is not a topographic saddle but a downdropped fault block which has preserved abnormally thick carbonate sections on the downdropped side. T!he Appalachicola Embayment persisted until this time in soatthwestern Georgia, although the basinal charactel:"isti~s, so clear in the underlying Cretaceous rocks, are not present. The Smutheast Georgia Embayment is evident on the Georgia CoastaR Plain in the form of abnormal thickening of the Sabine rocks; the depocenter of the basin, however, is unclear because of faulting. FDllowing the Sabine transgression, faulting, regression and erDsion, the Sabine rocks were removed in .part:; no early Early E.oc-ene history is shown by the rocks in the COST well. Lower !Eocene rocks were removed by erosion if ever precsent,, and rocks of the Claibornian Stage, late Early Eocene in age, overlie the Late Paleocene-aged rocks of the Sabine. -104- Furthermore, the Sabine rocks, from an outer neritic depositional environment, are overlain by the Claibornian Stage, the lowermost beds of which are bathyal in origin (Lachance and Steinkraus, 1978, p. 48). The foundering of the outer shelf area (as part of the faulting onshore) would result in a bathyal environment developing over rocks which were otherwise neritic, in a setting in which sea level was also rising, according to the model of Vail and others (1977, p. 93) (Figure 28). Late Early, and Middle Eocene (Claiborne) Ages Following post-Sabine erosion, the sea again transgressed over the Georgia Coastal Plain. On the Atlantic side, the basal Claiborne rocks in the COST well are uppermost Lower Eocene and are bathyal, reflecting the foundering of the Embayment. Lachance and Steinkraus (1978, p. 48) interpret the depositional environment of the lowermost Claiborne rocks, those which are late Early Eocene in age, as being from 1500 to 6000 feet deep. Few benthonic foraminifers were present, although the d~ep water indicator Bathysiphon eocenica and several radiolarian species were recovered. A rich dinoflagellate assemblage is also present, and very few spores and pollen. Following the deposition of these bathyal beds during the late Early Eocene, a dramatic fall in sea level followed (Vail and others, 1977, p. 87) (Figure 28) and neritic depths again occurred at the area of the COST well. The bulk of the Claibornian Stage is Middle Eocene carbonate with a little -105- interbedded chert. According to L.achance and Steinkraus (1978 p. 47) it is difficult to interpret precisely the Middle :.Eocene environment. The foraminiferal a-ssemblages contain few bethonic species, yet the chalks and marls are similar to those of the Late Eocene (which is interpreted as middle shelf (50-300 feet), although the absence o'f the larger foraminifers in the Middle Eocene may indicate wat-er depths slightly deeper than that of Late Eocene times. Clearly sea .level has fallen however, as the ro.cks below are from the slope environment. Onshore, on the Atlantic side, carbonate depo,sition predominated, up to 10 percent chert and evaporite. :These evapori-tic limestones are in an elongate, northeast-_southwest trending basin (Figure 19), essentially parallel with the faulting which preserved the abnormally thick section of Sabine rocks below them. Seaward of the basin., the :claiborne rocks 'B.~e thinner, and then become thicker. On the Gulf Coast side, where the Claiborne rocks are highly calcareous sandstones and carbonates, neither a d-istinct -carbonate facies nor obvious basin development are evident.. Updip, al-l of the carbonate rocks become sand-ier and pass into calcareou,s sands .~ The Tallahatta Formati!D:n., tt.~e lower unit, does not crop out on much of the Fall Line -but is over:lapped by the Li,sbon Formation which cnntains b.-me- stone ~ds within t -he calcare.ous sand-s,, and ex:t.e.n:d.s as ff:ar inland as the pr-esent Fall Line. Marine overlap onto the Georgia Coastal Pla-in is evident. -106- The lower Claiborne beds offshore are Late Eocene (Steinkraus, 1978), as is the basal Claiborne Tallahatta Sandstone in Alabama (Berggren, 1965, p. 279), yet the basal Claiborne,Tallahatta equivalent, onshore the Lake City Limestone in Florida, is lower Middle Eocene (Zone P 11) (Huddlestun and others, 1974, p. 2-3). This indicates that the marine transgression was very slow, as the basal clastic unit is time-transgressive. This coincides with the model of vail and others (1977, p. 87) who note the same occurrence on a worldwide scale. Furthermore, the chart of Vail and others (1977, p. 87) shows a sea-level fall within the Claiborne, and then another rise. This coincides with the distinctly different ages for the Tallahatta (Zone P 11) and Lisbon (Zone P 13), as the sea-level fall is during the time that Zone 12 was forming (Figure 28). The distinctive, elongate basin containing evaporite limestone and dolostone in southeastern Georgia is a result of Claiborne tectonism, but the nature of the structural control cannot be determined. The ridge shown offshore by the refraction survey of Antoine and Henry (1965, p. 608) marks the seaward edge of the basin, and it is on this ridge that the Claiborne rocks are thinner than they are in the basin (Figure 19). Antoine and Henry (1965, p. 607) suggest that the Southeast Georgia Embayment opened southward rather than southeastward. If the evaporite basin is a graben, essentially in the same location as the downdropped fault block which has preserved the thick section of Sabine -107- rocks beneath it, then the ridge would have been acting as if it were a horst, or at least as a stable block. The thin Claiborn~ section on the ridge could be attributed to either post~claiborne erosion and removal of sediments from the upthrown block or if the faulting were contemporaneous with Claiborne sedimentation, sediment bypassing during Claiborne Age as the basin to the northwest settled downward and evaporites formed in the restricted environment. Other Claiborne tectonism, if present, is not as evident. In the area of the Central Georgia Uplift, Claiborne rocks are somewhat thinner than in the surrounding region (Figure 19). This could be explained by a lack of deposition at those times when the uplift area was positive, or by uplift and removal of some of the Claiborne rocks during Claiborne time. Such ah event would explain the distribution of the Tallahatta Sandstol\e (which does not occur northwestward of the Central Georgia Uplift) and would accompany the sea-level retreat recorded by the biostratigraphy. Other faults may be present within the Claiborne terrane, but the scarcity of data make their presence undetectable. The well-documented Andersonville Fault (Zapp, 1965) intersects Claiborne rocks, 'but none younger. It is post-Claiborne and could be younger than Oligocene. Following the transgression of the Lisbon seas, regression occurred, and erosi,on S'et in on the Claiborne rocks. -108- Late Eocene (Jackson) Age The Jackson Age on the Georgia Coastal Plain and offshore, at least as far as the COST well, is represented mostly by a relatively thin, uniform blanket of shelf limestone, the Ocala. This blanket overlies the Claiborne rocks unconformably, but with little hiatus and little relief. The basal beds are the clastic Clinchfield Sand updip and the Moodys Branch Formation downdip. Where these units are not distinguishable, the basal limestones of the Ocala are sandy. Northeastward, along the Fall Line, the fluctuating strandline of the Jackson sea is reflected in the intertonguing of carbonate and clastic formations . . The rocks show that Jackson time in Georgia was characterized by a broad shelf of probably middle neritic, or even outer neritic depths. Lachance and Steindraus (1978, p. 47) have identified Nummulites moodybranchensis N. tuberculatus operculina moodybranchensis Bulimina jacksonensis Cibicides jacksonensis Siphonina danvillensis from the Upper Eocene rocks in the COST well. These are from a middle shelf (50-300 feet) environment, possibly slightly shallower than the underlying Claibornian Stage. Toward the southwest, the Jackson rocks are more deeply buried, and because of water-quality problems and dolomitization, they are not well known. Farther south in Florida, however, they can be divided into distinct subdivisions, but are still carbonates. Evaporites are known from the lower part of the -109- Jackson rocks in the southwestern part of Georgia, but few details have been reported. Tectonism during and following Jackson deposition is not well documented. Regression is shown everywhere; Upper Eocene rocks are overlain by Upper Oligocene rocks. This regression is shown in the model of Vail and others (1977, p. 87) (Figure 28). The isopach map of the Jackson rocks (Figure 23) shows irregularities in the thickness which could be attributed to post-Jackson deformation and erosional thinning, but the details are not evident. The cr:oss-section A-F (Figures 29-34) show that Jackson strata are regionally conformable upon the underlying Claib@rne rocks and are regionally conformable with the overlying Oligocene Series. The presence of the Appalachicola and Southeast Georgia Embayments can be deduced from fue general thickening of the Jackson rocks toward the southwest and the southeast, although the thinning of the Jackson rocks by post-Oligocene exposure and erosion must be considered in the interpretation of Jackson rocks in southeastern Georgia. Oligocene Epoch Following Late-Eocene sea-level retreat and erosion of the Jackson rocks, transgression commenced. Offshore, in the COST well and in the JOIDES core hole, Lower Oligocene limestones, clastic at the base, rest upon Upper Eocene rocks. Onshore, Middle Oligocene rocks are found to rest upon Jackson rocks along Ocmulgee River (Pickering, 1970) -110- and in the Gulf Trough. The overlap which began in the Early Oligocene may have continued until at least Middle Oligocene. Whether the first of the Oligocene transgressions was as far inland as the present onshore Coastal Plain is unclear; such rocks have not been found. The lowermost Oligocene rocks, mostly Late Oligocene in age, almost everywhere rest upon a post-Late Eocene erosion surface except in the Gulf Trough and on Ocmulgee River where they rest unconformably upon a postMiddle Oligocene erosion surface. In the trough, where Middle Oligocene rocks are present, they are dolomitized to the extent that the necessary paleontological information has been destroyed. Also, in the southwestern part of the trough, the rocks are so deep and the water quality is so poor that few wells have penetrated the entire s~ction, and the foundation. upon which the Middle Oligocene rocks rest is not known. The thickness of the Middle Oligocene rocks in the trough, however, and the lack of preserved clastic facies updip, suggest that the original distribution of Middle Oligocene rocks was once much more extensive than now. This is borne out by Lachance and Steinkraus {1978, p. 47) who note that the Oligocene Series in the COST well were deposited in an outer shelf to upper slope environment {300 to 1500 feet) , possibly from greater overlap onto the continent than the underlying Jacksonian Stage. This was deduced from the presence of a rich benthonic assemblage which includes: Bolivina floridana Bulimina sculptilis Spiroplectammina sp. -111- Uvigerina curta u. topilensis These pre-Suwannee Limestone rocks, the Marianna and Byram (or Glendon) Formations are upper Vicksburgian in position (Middle Oligocene) and are in Zone P-19 according to Huddlestun and others (1974, p. 2-3) (Figure 28). Following the onshore deposition of the Marianna and Byram Formations, tectonism, which included uplift, began and the Gulf Trough and possibly other faulting structures developed. The tectonism was accompanied by a global sealevel fall, and the lowest sea-level stand of the entire Cenozoic resulted (Vail and others, 1977, p. 87) (Figure 28). Such a low stand of the sea, possible uplift onshore, and the g.(imerally warm climate of the time (as attested by coral reefs in the limestones) (Vaughan, 1900) , resulted in the removal of all of the Middle Oligocene carbonates exc.ept for those which were preserved on downfaulted blocks such as in the trough and possibly those on Ocmulgee River. The erosion exposed the Jackson rocks everywhere except in the tr.ough and along Ocmulgee River where they were overlain by Oligocene rocks in the downdropped blocks. It is possible that the thick section in the troug.h is due to growth fault accumulation, but the evidence is not clear. Gelba~ (1978) indicates that the Oligocene rocks in the trough are different from those on the outside, and this could be interpreted that the conditions of sedimentation in the trough were different from those on the outside, conditions brought on by the contemporaneous faulting with the sedimentation. -112- The differences in the sediments within the trough from those outside could be a result of the structural juxtaposition of different kinds of rocks, resulting in different ground water effects, so that the rocks within the trough have been acted upon differently by the ground water than those to the outside. Following the sea-level fall and erosion, transgression again occurred, and the widespread Suwannee Limestone was deposited. Its basal clastic content attests to the overlap over the Jackson rocks and over the Middle Oligocene rocks in the trough. No planktonic foraminifera are included in any of the published faunal lists of the Suwannee Limestone, but Huddlestun and others (1974, p. 2-3) indicate that it is Late Oligocene in age, Zone P-21 (Middle Chattian) (Figure 28). The extent of the Suwannee overlap is not known as erosion has removed the updip rocks, but the facies patterns indicate that the overlap was very extensive, more possibly than occurred during the Sabinian Age. Late Oligocene rocks in South Carolin~ are in Zone P-21 (Hazel and others, 1977, p. 75) and these, like those in Georgia, are shelf deposits, with none of the updip clastic facies preserved. Following the deposition of the Suwannee Limestone, tectonism, including regional uplift and continued faulting within the Gulf Trough, occurred. According to the model of sea-level change proposed by Vail and others (1977) (Figure 28), this was a time of continued transgression of the sea upon the land, globally. Since Georgia at least was -113- undergoing erosion after the Suwannee was deposited, uplift, rather than sea-level fall must have been the cause. If the rise in sea level were accompanied by a rise in the floor of the depositional basin, clastic sediments would bypass the area, and the resulting carb.onate deposits would be especially pure; such is the Suwannee Limestone. Above the basal clastic rocks, the Suwannee is a remarkably pure shelfdeposited rock. Once the rate of uplift exceeded the rate of sea level rise, erosion began, and the Suwannee was extensively eroded and thinned (Figure 25) everywhere except in the trough where continued faulting had preserved it on the downdropped blocks. During this time (post-Suwannee deposition) some of the faulting shown on the structure contour maps occurred, a result of the regional uplift. This is particularly manifest in those faults which have been truncated by the erosion surface. During this event, or possibly later as there was another episode of uplift and erosion, the Suwannee was completely removed in southeastern Georgia in the area of the Peninsular Arch and considerably thinned offshore. This uplifted area resulted in the further thinning of Jackson rocks after they were exhumed by erosion which removed the Suwannee. This is the area of the Peninsular Arch (called Orange Island by Vaughan, 1910, and called the Suwannee Uplift by Weaver and Beck, 1977). Weaver and Beck describe post-Oligocene events in great detail. -114- During the time of the regional uplift and erosion, sea level continued to rise, and eventually the Chattahoochee Pormation and its carbonate equivalent, the Tampa Limestone, were deposited upon the Suwannee. E. Applin (1960) describes post-Suwannee Oligocene rocks in the trough, as does Herrick (unpublished GGS 1825) ; these same rocks crop out in southwestern Georgia. The nature of the contact between the Suwannee and the overlying Chattahoochee Formation is apparently unconformable, as the Chattahoochee has a distinctive basal conglomerate and the formation contains clastic material throughout. Huddlestun and others (1974, p. 2-3) note that this unit is post-Suwannee in age and is in the upper Chattian Zone P-22, (Figure 28). Almost everywhere that the Chattahoochee Formation overlies the Suwannee, the latter is relatively thin, suggesting that post-Suwannee erosion had preceded the Chattahoochee transgression and deposition. Following (and possibly during) the time of the Chattahoochee transgression faulting in the trough was reactivated, as the Chattahoochee Formation and the Miocene rocks which overlie it are exceptionally thick within the trough and are relatively thin to the northwest and southeast. Weaver and Beck (1977, p. 8) note that the Chattahoochee Formation in Florida is' both Late Oligocene and Early Miocene, suggesting time-transgression. On the Atlantic side, Lower Miocene rocks overlie Eocene rocks or Suwannee Limestone, no post-Suwannee Oligocene rocks are present. Figure 27 illustrates this sequence of Oligocene tectonic-sedimentation events in Georgia. -115- Neogene Period The Neogene Period includes the Miocene, Pliocene, Pleistocene, and Holocene Epochs. The events which occurred during these epochs are outside of the scope of this paper, but some of the more obvious structures and sedimentary events are described because they represent continuations of structures and sedimentary events which were first manifest in the Oligocene rocks and time. There are some structures which were formed after the Oligocene sedimentation and may be pre-Miocene. Gelbaum (1978) and Weaver and Beck (1977) described Miocene rocks in the Gulf Trough where they, like the underlying Oligocene rocks, are abnormally thick. Continued formation of the Gulf Trough is shown. The anticline offshore was first detected seismically by Hersey and others (1959, p. 450) who recognized a flexure that they interpreted as being on Upper Cretaceous rocks. In the s~me general area Antoine and Henry (1965, p. 607), also by seismic interpretation, detected a surface which they considered the top of the Oligocene and which appeared to be arched upward and had a flat top, as if planed off by erosion. Schlee (1977) describes this feature in great detail, having further information from the JOIDES core hole nearby. It is a post-Oligocene feature, as Oligocene rocks are absent from the top and thicken seaward. The feature may be related to the tectonism which produced the removal of Oligocene rocks from the Peninsular Arch area. The Oligocene rocks are -116- unconformably overlain by Miocene rocks. Other arches, or anticlines have been noted in offshore or shoreline areas by others. Siple (1967) calls attention to a structurally high feature which he calls the Burton High, and Heron and Johnson (1965) describe a similar feature, possibly the same one, in South Carolina which they call the Beaufort High. Furlow (1969) detects the Tybee High in rocks below Tybee Island, Georgia. All of these features, however involve Miocene rocks and so are younger than Oligocene. Winston (1976a) indicates that the Ocala Arch is not a tectonic structure as theretofore thought, but is a consequence of eastward tilting of westward-dipping beds which, when considered with the anomalous thickening of the Claiborne rocks below, has resulted in a structure in which the upper beds appear to be arched and in which the lower beds do not. Such eastward tilting can also be seen in cross section E (Figure 33) where the basement surface between Lowndes and Clinch Counties (GGS 3120 and GGS 338) dips westward and the overlying contact of the Comanchean Series, pinching out against the basement surface, dips eastward. Regardless of its prigin, the Ocala High (as called by Weaver and Beck) is a post-Oligocene feature, as Oligocene rocks are involved in the deformation. Most of the Neogene rocks in Georgia are Miocene in age. The Lower Miocene rocks, where present, are generally nearshore marine sediments and lie unconformably upon Oligocene rocks; Middle Miocene rocks rest upon the Lower Miocene rocks. Following the deposition of the Middle Miocene beds, uplift -117- I and/or sea-level fall followed, corresponding to the low sea-level stand during the Late Miocene of Vail and others {1977, p. 93). This is represented by Upper Miocene clastic rocks onshore, which include terrestrial deposits of deltaic and possibly fluviatile origin. Miocene history and tectonism are described in great detail by Weaver and Beck {1977). Pliocene rocks are very thin on the Georgia Coastal Plain and are for the most part shallow marine deposits found in the extreme southern parts of the region. They may also be present in upland fluviatile gravel deposits (Voorheis, 1970) or as fluviatile deposits in river valleys (Herrick, 1961). During the Pleistocene, overlap by marine sands is identified. Herrick {1965) discusses the Pleistocene rocks in Georgia. No marine Holocene rocks are known onshore, as transgression is currently taking place, but extensive swamp deposits, such as those of the Okefenokee Swamp alo~the coast, are Holocene. Post-Miocene faults (possibly Holocene) have been documented by Prowell and O'Connor (1978) in the Augusta area and by White (1965) in the Piedmont of Meriwether County. Lance and others (1977) describe the occurence and distribution of historical earthquakes in Georgia. -118- WELL LOG ANALYSIS One of the purposes of this report was to identify potential reflection surfaces from an analysis of onshore . wells, utilizing the geophysical logs available accompanied by an interpretation of the lithology of the wells. These reflection surfaces may then be correlated with the seismic reflection surfaces determined from the offshore surveys. There were wire-line logs of 40 wells from 24 Coastal Plain counties available for analysis. Table 1 indicates the types of logs and scale. While the basis InductionElectrical log was the type most often available, sonic logs were included for 16 wells and density logs for two additional wells. Phase 1 of the analysis included a preliminary lithologic interpretation of all the project wells, based only on the log characteristics, and a tabulation of the horizons showning a strong seismic reflection index. Phase 2 was the preparation of SP and Resistivity Logs to a scale of 1" :::o 100', drawn on a standard presentation from which also included lithology and formation data. The logs are available for review but because of reproduction problems are not included in this report. Phase 3 consisted of an examination of methods by which the well logs could be related to seismic sections. An effort was made to recognize key horizons, not only because the logs were regularly used to support and refine stratigraphic -119- correlations, but also in the hope that correlations co.uld be made between the logs and seismic sections, especially seismic data from offshore lines. Considerable attention has been devoted in recent years to reflection seismic amplitudes as potentially diagnostic of the physical characteristics of subsurface zones (Sheriff, 1976). Because seismic records as well as certain well logs are related to velocities of sound waves in rock layers, it is possible to correlate the two methods and to predict the relative amplitudes of one record from a study of data from corresponding subsurface depths obtained by the other method. The most useful tool for comparing drill hole and seismic sections is the Continuous Velocity Log (CVL), also referred to as sonic and acoustic logs. Where such logs are available, direct measurement of interval velocities can be made, and very good estimates of the reflection pattern of seism~c waves in cr0ssing a lithologic boundary can be determined. Essentially, this is the basis for constructing "synthetic seismograms" from well logs, a process now available commercially from a number of oil field service companies. CVL logs became available in 1954 and very quickly the concepe of synthesis of seismograms from the well log data was proposed (Peterson et al., 1955). Subsequent workers have reported on methods and applications (Sarmiento, 19:61; Sengbush et al., 1961; Harms and Tackenberg ,, 19.7<2-; Seien.tific Softwa~e Co., 1975). Approximations of the velocity logs can also be made by transformation of resistivity to -120- pseudovelocity logs (Rudman et al., 1975). Zones characterized by large effective acoustic- impedence (velocity x density) contrast will return stronger amplitude waves than will those of low contrast. Thus the more prominent reflectors will, providing the zones are thick enough to register the velocity change, indicate a substantial difference in propagation velocity between the adjac~nt layers. Velocity is strongly influenced by rock density and pore fluids, and can be a key to rock type. For example, the interface of a water-bearing shale (low velocity) overlying a thick compact limestone (high velocity) will give a strong, high-amplitude reflection. Amplitudes are influenced by a number of factors in addition to reflection coefficients, such as absorption losses and scattering during transmission through rock. Also, reflection amplitude is affected by data collection and processing. The current state-of-the-art is such that these effects cannot always be compensated or evaluated, so that precise quantitative determination of reflection coefficient is not possible. On the other hand, amplitude relationships are preserved in the seismic sections, and relative amplitudes provide a valid basis for several interpretive techniques. They are of special value in studies of lithology, fluid content, and comparison of well logs and seismic sections. It is this latter application which we have emphasized in the present study. -121- Reflection Coefficient. If the seismic wave is initially traveling in rock of density PI and wave velocity is v 1 , and it then passes into rock of density p 2 at velocity v 2 , a portion of the energy in the wave will be reflected at the interface and the remainder will be transmitted. In the case of normal inc~ence, the reflected and transmitted pulses have the same shape as the initial pulse, differing only in amplitude. The ratio of the amplitude of the reflected wave to that of the incident wave is termed the "reflection coefficient" (R) . Ar R= AI where A = "pressure amplitude" of (r) reflected and (i) incident The amplitude of the reflected pulse is determined by the change in the density-velocity product between the two layers. This product is frequently called "acoustic impedence" of the rock. R = P2 v2 - P1 vl P2 v2 + Pr vl In addition to specifying the amplitude of the reflected wave, the expression also indicates that the algebraic sign depends upon relative values of the acoustic impedence. Thus, when the wave moves from a medium of low acoustic impedence to one of higher acoustic impedence, the reflection coefficient is positive, and the incident, reflected, and transmitted waves will all have the same polarity. If the reflection coefficient is negative, the incident and transmitted waves have the same polarity but the reflected wave is reversed. -122- In constructing a synthetic seismogram from a CVL log, several manipulations are made, and a reflection coefficient derived at about one millisecond intervals. Thus, for a 5,000-foot well, there might be 1,000 incremental data points. Clearly this can be accomplished only with the aid of a digitizer and computer program. For the present study we have visually scanned the logs, noting sharp velocity boundaries at which R was computed. Experience indicates that if R exceeds + 0.10 there will be a strong seismic reflector. Since the principal objective of this phase of the study was to predict which stratigraphic boundaries were most likely to be recognizable in seismic sections in the Georgia Embayment area, we have examined the nearshore wells, with the following results (Table 2). -123- Table 1. well Logs Available for Analysis 2 - t"'UIO' j g no 1 ..-.n-:.hy county. llwtbh oll tl w. r . hl,l.:ut 1j11. ,!I\ .Jm l ~1 ~ ~ ~ 1 HJ~ l1 ! I t i I 3 l l.ltl ~.udn Co-..nty. Pan A=dc::a..., Pet:rol.~ tla llruoo c:.up Utt Cu:Jcten C:ow:~qr . Pan AIM:-.!.can httohua .S tl.-"C Dnion c.a.p 171 ~ l t.crs C:oUDey. Sou= PIM OU tl o. c. Kia.U ttl c.l.1...a.c:b Cowtey. Jhua~ 011 U Ali~ P\ul 9r~ a ll .Uic:: l+.l'91:~ rc;.;s Zto. U7) Sl27 eot!n caua.cy . 0\ev"Z"oa Oil tl ove.S. Pl.tU et. l 101 C:.! P C:2~ty .. len-Mea.. n Cecil u UO _.~... ~ <:ollftty . Rlet~az oU co. U G. E. OO J . l u .... ll2 O.cnur Cou.,~. 3. A. Sealy t2 !pi.,;ill ZOI Den~\lr Colll'l~ ealary O.V. Co. f l 3. \11, lcot.~ ,....,.. Dod, JlO!I Co~.U~~y. At..l&Du Cu Li9ht. tl I 6 L .J li:J ~9""rr.:y Ca~U~qt. J. ll. Sealy t-2 lhrn.o14 ~: Co ~ Uu tarlr C ~1.u1 ty . H :--:h .ko:2y J. An4euon tl Ch t Uctr..ll ern l'apr ~o . .lUI lady eDwtty. ~- a Jl. 3. J.ndenoo U Or~ Noc-then Papee Co, l.3 l, Uff -Glyft.D County. Pan Aater!ou ~. Co . U Qa..loa c.amp nt Ul u rullD ~u~ Gl}"''Ul C:~q. 'ftlltii.Dll OU U.:T Qn.i.cn Sag~' 2 Cu:~j~ Paper CQ .. ClyM CC,unty. 11\.able Oil tl-S1' W. e. Hc0oa.al4 'j Je1'! Davi COW\cy. OleV1'0G au u 3. t. ' l:laclAlr :t..u.riLDe c:ounc:r. C:.hpor K!q. Corp. t1 ~ll'ce HCC&i.Q .. s~i uv.r-:a\11\f:'ro Hun~ h'UGhwa t1 .J. ,$ .. t.ovflde e~""'CY ~lhuu: rec.rol tl t..-n;- l . l 40Llo tdvt\dee C:OW1 rf . llant: ht:'ahW! n z ,$ ttuuay, J~:. Ott LoV'r\d.ae C:ounqo .. llu.nt: Peuohu= U Jck Colo !Mnd UJ C:Cit.&nC)' 0 lhin'=. u~tei.III ~ U-A t.. J!"o.L . . . . ua ~i't:J.~ ~-~:; J. !. -.uhV!o;-:! .3 f'' .I Ul Puluk!- eou.ae,r. S..ittht:on ctr1lll119 eo. JH 'fl.&a.a ~ll> Pol:uld. CO\a.D~. Ao:l.anu c . . t.i9h't c:o. fl 4dtt'J.tll oSI ~~;~~~i:~~n..rn~ll Drilling :a. ... "" .. 001 :14aa.LDole CO\U\qt. S. e. Dunlap U Uund~ I : SULacb C:OIU\ty: J!~le ou .1 J lo.Uy 711 tt...v t t:: C:ouncy. Be!.:~oa. . l~l t1 W, C: .. lrac!ley co. 0 ,a l ' ,s; t 0 0 .o llU -Trlcz:s.u COW1ty, t. A. ' DUrll&.all l.t. lraM :t. If, SedJ.,~c:.k 1Jo '~1U;!:nt.~~,ili.~~U Drilli~ co. ;:z ltcl.:; Ul .. ;:;:~ "uNih Oil 11 Onion hq- o ,J 2. Ufl warn covrt t: 'r' . ftuJ\t ~:.,1WII n 4 1 lc,\t I HIA" h .\JII' ~c>. UU '"Nyn .eaunt:y, Wm. llt.-) .,J.'I U 4 C" l..:ot.~ l,J - lo 11iil1d h,.l' Ca. 'OJO ""l ,r CcWit)' ~ !t)ut.'"lr:11 N~~:.u.nl C fl ltatuu "!'ovn1 lOU '"" L .:- C':1\LI:1ty. Scn.1thern "'t.uS.al a U D.r. :1. lo MeJia ..-124- Table 2. Tabulation of Reflection Coefficients Greater than 0.1 Well GGS 719 - Glvnn County Cased to 619' log depth. Subsea elevations: -916 1 -1857 -2088 -2715 Top Claiborne In Sabine " Top Cretaceous (slig~1L!y 1ess than R = 0.1, but recognizable as a reflection surface) -4685 Well GGS 724 - Glynn County Starts at 713 1 log depth. Top basement Subsea elevations: - 827 In Jackson - 950 In Claiborne -1669 In Sabtne Zone of several thin reflectors -2130-2220 in Sabine -2405 In Sabine -3395 In Gulf -4483 In Lower Tuscaloosa Fonaation Well GGS 1197 - Glynn County Starts at log depth of 90 1 S~sea elevations: -1030 -1086 -1554 -1687 -2000 -2134 -3568 -3904 -4270 Near base Jackson " In Claibo:ttne " " In Sabine near top In Gulf Top Tuscaloosa Formation Near top basement Well GGS 1198 - Camden County Starts at 1503 1 log depth. Subsea elevations: -1584 -1604 -1682 -1942 -2152 -2950 -3312 -4202 -4587 Near top Sabine In Sabine " " n In Gulf II Top Tuscaloosa Fonaation Top basement Well GGS 876 - Charlton County Starts at 1270 1 log depth. Subsea elevations: -1866 -3696 -4088 -4455 Well GGS 651 - Wayne County In Sabine In Qulf Top Tuscaloosa Formation Top basement Starts at 230 1 log depth. Numerous thin, closely spaced low-velocity layers in section bet~een -380' and -920'. Harder, thin-bedded limectcnc~ predom~nate between -920 1 and -1400'. The top of reflection Cretaceous is recognizable coefficient is not strong a (R t = a bout 0.80 ). 2355 ' ' but the Subsea elevations: -3605' -3730 -4155 -4307 Top Tuscaloosa Formation Tl'1 Tllscalc-:-o::a Formation Below TuscaLoosa Formation Tcp basemel1t -125- - .. .. . ~ ~ ., B . . .. t .. . ... "' ..... . . ., " C1t.1 ~tu:loiiiLfltll'l ..-~ ,-:: -~;~\ QfjJ" 1 E'- !:OL.UM.Bfll - , \ or ' .... ~'fl .:..._ Wl:t"RE,.a.1 1 ~ 't <:> ' __, ' - .. , ~ ->:.~ -~ - ~ ~J0;MO'~ I' ': "1, ,. . I WA~ IN-JTOH ~i ' ~ ") BURflf '!' ..} \ - 4-f .-... ,/ l "c. ~ - -- ' -: ! - \ "" '~ IU"''.S-Qif \ .... -....---~- \._,, ... ~.. . - -:J . '~'t'.. ':I \ Jtnl(f(S ' I . :':' ) < ':' \. .!> CAAIDRO ;---: ~ .;:o._ .. _, ' - - .JormsOr. 1 StR(oJTh "" o, GEORGIA GEOLOGICAL SURVEY WELL NUMBER "" GEORGI A GEOLOGICAL SURVEY DRILLING PERMIT NUMBER a OCEAN PRODUCTIONS, C. O. S.T. NO. I GEORGIA EMBAYMENT U.S. GEOLOGICAL SURIIEY ATLANTIC CORING PROJECT, 6002 \ '\ .~o, c... ':J .!. \ ~ -~~~t~" ,,~ , r\j T&rr.CI~,...- / - ...J..'',:';r~)J, ~~!;~'fOo 'I"" ; .~-4'JCI :t . \ , .:. 1-I ,,u.eoN :I - ,_ttoc-: ,.- - -!~: E ::: ,,4..,tiN -\~t'-),.e,_~".o,' , l I ~ ~ .J.J.-.fs~U.:H,..d....!.-..~:.~~...~ ., 1 " '~...- , ~u1 " 1- oooL-1 ,. !loJ' '\~ .i1'l ~ XIII : ""!.~~s~~~.i'i '- "- 'U 'I t.-n > '-">~\--;-' I :!- -- l ~ / "-i"~\~~.'..To.o A.l._. ' "' ' , _ .). -.!.IN \ ~~~ ll. .... ~.. :., ,_,.:.~ w ': E~"'st .. ":' :-:.:i r-- -'<. - I fiUtrR ~1 ; POttti( .-.\ ._..ElE\_j ~"" / 700:85 ~ . ,") .~ S1-:W4Jtl ., ~,\lii~rr.=-: n. ,;.' 'l '' , .., -'--:~..;- - --.~,.~ , 1, ' ./ 4~ - " '-......'\ ~"' ..__ -... .' ~tAT"Trllli ......_ - - , r\, .. ~~~ I . '-' ~~';.I,,_ j -.:':'.ut r-....,.tiu_- '. -"',.. l-...-- - mt::. ..:'.t-a.,.;.- v I \ Cl-'Y) 1 - I ..... u ~ - -- - - ' -- - -- - J -.t ~ -~..;:.:... . ~ ,. .,.J .l i DO< \ ! fEflA!U- .. !(. . . 1 ,., , !- -'. . . .. JhSP I --..ir-. ' ---. rs. \---- . ~ ~Lr:.o.t . ....~ ' .~ '"'-' ' f [i.FA.IR r-.S-,...,._,-..~ / ; 1 \ . " ',,'.. ' t..'!_':' S}....v~.:j"v,:.ov~~ 1 ,. ... ... _. j t-.,.'"."~"-~ 1 -: J n" Lt;!'G ..... . ,.,.. ,._., . - r; T,jl< ' i\. ~'" rH-I'-<--~ , : j ; ~::..,c:----; --~-1. . . . . ~ F Y:.;hiO I ~ ', ........, . ~ ~11 L ____ _f'...~-~----~ __ _. __ I- """' .. ( ,. ..- , ' r:t "J- l~ h v'J 1' J ~ -~.~.. _.....7' -.: '!" - c.:.;;; , !. ~ ~--= ._ t 1io ~t.rtoOUt. , , \ , - " : _go~E AMP'l ~7 ..~~ __ _!!'YM---~-r--- 1 .., . r ,....J ~ ,_.~~~,. .. I' - ~ -.....,"-a"---- ~- '"'-- t' I. t =i.: ... , ..f_. .:____ ;{ "..!'.I''';-I.Nt-"l~'.-...i\.'.t,...r...~.r_. .~-~.f--..~o/...F--fE-.-~::;~.- ----1~IL owst . Ji',-... \ .:m_ : II'L(IlH '-~~ __,. .,L "" l -, ~ WA.'I'I1!! "' " -~ .. 1-l+.i.:.. ~~-E:A"~.::.I. \ _,_-., ;. - .. - u-0.. ~'\: _,..., - ...~ M' ... ! ~f0:(<14 '" ,~:..,~ ~:.... ,..... L 7 ...... , ,. ~ "';_ ... _cl :""'t- ~ -. ~ITCKI:U. l!f"t"GC~ ~ ~ ~ fi .. _. -- - -,-"II..!. I I . .- . I I "- ) .. .:- ~-~l- ~,_ ,.. 1 /1 ,~-~ - --- - _j -,--- -r- - 'I e , , : I .... - -- ---1.,.'::-:: ;.r::.:- ::. ...-.. -- , 'n~":.~~t i I .., :: M 't ( 1: ''\ Bt:HA te t'll - . ,:. I .. l ' :-:,.\"T ---t'."- ~~ . ... ...,. , ~~ou~~T. I'JI w ro: ' , " - ,_ ..t3. - ~co~ 1 M: ; ~ f'1~ -~- -u ...: 1 !""'n-o.t... C'l j ' ~u :.t..,! -- .t. ,t-I;.;J - -\ \ \ _.. ... .,_ \ ~~ t;.C RF; .. ~ ....... P~!.:_ET t " y......nJ I """' - ;r,. H';n"-1~.r!tt::J~l~~-'~f''.~ ! "-V r ---- ~- u -- _.. j \ - ' I e. _. ~ .:,_L- ~ I i~-}CH \ 'f "i' jf:_lT!JR ( :too ' -l:.- - tU G;; ILD' ! ,lrtQ-:_-~S ~ S;A-C~u$r '"".\.\.-. . .."\ _,.1 : 'fS\ i .. 'l '" I~- w J CIIIULll)l'l' ~ u:'f-t.... 1:-A MOEN , ' ~ :.. 7 - ""':__:"___ , _ _ ____ ------ J ~I......;. '::..~..\-.lOWHb5 ( j :: f' 1 h"ck.s._f&- '~~---- '-' --.. '-~.__:~~..,~. - - ..... ..::....! - - - - -.....'l _ _ ) . _ _.. _: ~ : _ - .. . - ~ ll . fMCIIt'f UIIL'tll"SITT- llpilltA UUTM'ffl~TIIt tOLLI51 Figure 1. Index map, Coastal Plain of Georgia, showing localities of wells. "BASEMENT" (POST TRIASSIC) SURFACE CONFIGURATION r - - - ' .....~ . ~, elevation related to sea level (sl) numbers in teet ..I... N -....] I B lOCATION MAP '"".-=--... -~J--. -.Jf \ \I. ........._ ---------\ \ \ f ,. 110 JO 4,0 1,6 a U 11:1 1 ' ' ' ' 1 N Figure 2. I !f & rr \ \ - a toOl l ~ ~~ --~./ ,r-~ ~ ..., ... -___ .."'\ ' -s' . .1'\--~ ' I r l"'~/ , .. ~!"::~: . y J . ~} ~ --- ij , .l - l'"~ r c... r~~\ ;-~ . - ' , ,'.\.....,- ,. '\ ...... . \._ _ '-."i\. ~ ' '\(, ...._ ~ f _.---- -\- i ? r f ;' -- -- ' .... ----"" - I ,...~.\. \'.) '~~- ~ -' , r " " ..-- .1 \ --.. . ' J ~ ~ I - ">.,,} " "''--;-- '"{ - ,\--'r ----~ -~ . ~ . , ' ~ - '>., - r /' / _._ - ' / ~ ' c.-~.-,\,._,:_,'-_1'n~.y-) f., - l 'r,_::- - ' ,--. . . . ~ -, ..._ \ ~ c ~ \ ~ Y f) - y . '-,~ f - z / _;- ~ ~' '> ' ~ v~ .- _ 1,:,; t 1 "' I ' ' - Q '\,, " CA) "\' . \.. 11.t. , i ..._ ( ('\ ,... / It')\. - "' - - ' 0 ~-A- ~ < . . ~,. , ""' .... ,., r r -' ~ 1 ( - - , <'- ' ).. . .- . \,., _ / ~ I ~ ' - < / / / ~~ \ ' / ..... ~-- ' / n...".\.v :J, ~/ ~ ) Jt.i.. '. "-- ~ - ' ; -- ' - -- - - , \ -- ' 1 .',!~ -. -:.ee ., G'l \ A\ ,- !' I '" I - ~ ~.{._ ' --- - --- -- -.. ' "-T- = ~--- --.- - .... ~ o- - - .... \. . . . ' r ' -' "1. I 1J r -:_- _, r ,- ../ ~ 1. ...''\ . - - -- !',.,_ - -- - ~i - --- :-----... - - ?' ~ : ""l,-_._. L :.;- Gr Y '..... )'~ '_,'~-- - o - - - ,, ~ - - . / - / , \'.::l.:.:./"..<..~.'..,0/~/- (")~-/~~7L'(\"','---,/~,~.r.--'?y;.,(.l;!.'~./.1_-"-r~",~"' __,. .... - ~- c;:, - -, ;- i ~. , _ : CHATTAHt>OGt;~~ ~/ ~ .:-: ( i ~MBAYME.N1:-~~ ' - ' . .-- . . \- - ~ \ '. "~'! 1 r~ ' >-,_ , J - - " _ -. . ~ " I 1 - - - "9'-..~~ - SOUTHE:AST - -~ {-GEEMOBR~AGYIAMEN~'T-f;'\\ .... - - - - - - -. ".. L \ \_-- - - - :.:- - - - - - - 'J - - - ' -- \ ~h I \ -- 1., \1 ::- I --1 - . . r.'----,~~~--~=----...-::;;..~,-.f--""PEN --- IN -SU1=Aa~ i\F'--~-.....~--~r:':,~jf ; \ '; AACH \ ) 1\<.,.j figu.~~ ~~ St+u.atu.re~ on th~ ba~em~nt, QQ~itil Pl~in ~t Q@er~ia. 35 SIMPLE BOUGUER GRAVITY OF GEORGIA by Leland Timothy Long 1972 85'' " I 82" Areas of aeromagnetic coverage. Figure 4. Simple Bouguer gravity map of Georgia and outline of areas of aeromagnetic coverage. -129- ~ 1-' LcQ ti CD l11 Ul() CD::T ti Ill 1-'ti CDrr Ul Ul ~::r I::lsl 0 ~ p, 1::-s' .O...LQ P.::S CD ti 0 s v CD ~::s () ti .... 0 Ill ()(T ~c Ul ti CD 0 1-tlC Ul rTCD ::TO. CD 1-tl GlO CD ti 0 ti'd LOti I-' CD Ill I n cGl 01-' llll-tl Ul 1-' ....!IlTl i:l:sl () ."..U.. rtoi lllrt 1-'117 ::trno 0 c to () 0 s :I:lsl () ::T CD :I:lsl -OET- LOWER CRETACEOUS? LOWER CRETACEOUS COMANCHEAN COAHUI LAN COMANCHEAN LOWER CRETACEOUS LOWER CRETACEOUS COMANCHEAN JURASSIC? LOWER CRETACEOUS APPLIN AND APPLIN, 1944 PRESSLER, 1947 cG) SOUTHEASTERN r -"TT zJ=lo GEOL. Sot., 1949 ~I .a..!, FORGOTSON, 1956 en ~I en MURRAY, 1961 0 J=lo HERRICK AND 81 en VORHIS, 1963 ..J=lo ~I APPLIN AND APPLIN, 1967 ez n 0 z NEWKIRK, 1968 LOWER CRETACEOUS SERIES UPPER JURASSIC COTTON VALLEY GROUP? COMANCHEAN? COAHUILAN? CRAMER, 1974 GRAY, 1978 THIS REPORT .r~ ,.,..~ ~.,. ~... ----~,, ,......__.;..-' \ COMANCHEAN SERIES (AND OLDER?) STRUCTURE-CONTOUR MAP 1 ~ ---~! J'. / l'.- - ,.-.,. , . [ A \ \ I . OF THE TOP \ - ;---~.,.,......J\ ' \, \ "\" \ ;>.L~ . ' ' ,. 1,0 10 .... y ;' ').' '*') ftiJ.OY Jete7.au ...\..-._......... / 6 -J~'- r I .../'>-' 1 N elevation related to sea level lsi) r- .. "( -~ ~( o rocks not present "' downthrown side of fault numbers in feet ..I.... .w..... I t) LOCATIQN MAP " ',(// \"\. \ ----\ /\t:~- X ' ~ ' \ , /' .-.{ ~ v' -;::<:.._" "\. \ \ ' .&!- ... 'r:....,./'.. . ~ t J I'-..,., I ; ' " I ..... ! - -""- '. , ' ~ ~ .. 't- " . '-"~--~Y ';--.- -c~--~ .../J' "' ' rl l- ~ g , ,tZ .. --.J,.; r - ' ~....,".'r\'-;0--~ 0 ; . o t' :: -l __I,._o . :' ~ ~r ' .. - ,-.1 --- ':'" d - , - - -'-' "jO t. . I 0 "0I.,- - - I' ,r.",;",..'..__ ,..0_.... .. 1I i ~-- - .l - _j' \ I I /' "HJ'O I ' - )I Figure 6. --.. ......... ~ t 111 .o ct sp ....! I , ' q l : ./ COM~~HEAN SE~I~S <. ~~H olti~R- ?' ) r- --- -.1.... .~ _LI ,____( ~ :~-/y ~ 9 ... 11 !O Y !p Y 7,! U ~- -.. ~'-~- , .-.J ..., J( lilln ISOPACH MAP . ...-, ,.. .--..... .... ... I ~- -- \ ' I ' . . ~ ""', ,;." , _. '~--T' , .... .. f-\~ ....J'........... ~ 'I l " ....., A ( \ /" i -- ~-v J--"' I ,\ l ,.---- 1 N a ;~,, I - 0 ' I fw-' N I ~ . ; ~. ;, ,, ;H:ri l ~~~!:'' ..: \,. :t; 1 :.:~ ~ioo: !Jiii:ted to sea level (sl) :: wl;ks.m~t>Ne$80t .: '"'', "' dOIN!Jlii(O!Nn ,$ide of fault numbers in feet t) LOCATION UN : ~ (_ ., ~ l ' t.... -----l \ ~L-- ; ...---- :...1 ...::,.:.i.?--~ ~l - .oo ~ l, _ """ ~ ~~ (. ,...,_ - :~.d ~ ? / ) .- , . ~ - .... -I1r- r ' 1 . "' I -- ., ~-,- - --,lr--~~ ........,'.I . , ~-'.-~--\ ' rom~ ~ - ---? ~---,....... \. ~ , \ ') \ ---1 -.., l ' v. t.:t7 _r, . ")...,. J f-- - 1,_.._,_ \-~ ~I. ~ r . \ .. II \-~- - ,....._,... , ,. I,\ : . .. ~ ,./ -: \.-"\ "'ll<-. -. ~ ;......o;.,r - ..., '\.. ' ~ '.r\... ~ \. ~-- ......,.. 0 . I '~() ./',_i._., f:i:\ . - - 0 --- ;,- -oyr' C...... ~~ -~ ' --1-t __ __ "'~ r- -~--; ./ I ,. . _. , ..... -,, ' I I"~ L . \ ', ;! I ' I, I' I I' -.L_____ --L---Il - ''"J! L .. __ .:f.~- I --L - r- :.-l.,... ' o . - r o r ,J-.g___ ! ,~~..... I ~ . . ,....-/'\ ~ IWtOIIW _ ..c- f 1 H 1'1 ? ~~ a l h K! f I " , / <> \ t_.l Figure 9. ~ \ -.UTO . ~ ~ i l z . i I I i --, ' E! 1 -135- PERIOD .EPOCH AGE COSMOPOLITAN STAGES GULF COAST STAGES OUTCROP THIS REPORT Late I wf-1 "I ' I ~ c ~ tJt cu u 2 0 0 0 Q. ~ Eorly l I I I I Thanetian Sabinian SABINIAN STAGE h- I -.- 1-r' I ..- 1-r r-r T"O ,--, r l r-. - Danian I Midwayan I II lJY CRETACEOUS LATE MAASTRICHTIAN L-'- Figure 11. Time-rock chart of the Midwayan Stage, Coastal Plain of Georgia. I ~ w ' -....] I MIDWAYAN STAGE STRUCTURE-CONTOUR MAP OF THE TOP elevation related to sea level (sl) 0 outcrop o rocks not present "' downthrown side of fault numbers in feet 2> LOCATION MAP r I I )_ /"----4.. 1~ ./ ~ _,.-" ~ \ ..,....... I '!I J, JO 0 If lh o t ~ y y t I I ! N ~ ~-\ _,.'~ t Figure 12. 0 ~Y"""v-n Giao.;,u....,.._.._OOI..l.Mt .; --~ ---'" :< -~ ~J ' ~~ t ,, y J. y t,p . , .... } ! I# y .y .y ,, 1 r.! " ...,. . . . ... MIDWAYAN STAGE ~y-~I \... '.."'"'\ o ~ - - J / '\ ~o "t ISOPACH MAP _.J1 Q ,' I 0 "-..__,~ . .~ ~s. ' o "\ \ , r---y / \ I 1 I wt-' (X) I thickness o Qutcrop o rocks not pre"nt 10 downthrown side of fault number' in feet 0 lOCATION MAP ~ ~ \J L ) .'T1 ~ 1 /.- ,' J , \ ( "" -- / I \ ~ ~- ~--v - ~ 0 .... l--..... ( ~- ~, t /'v I" \' ..-, / ' 0 ....""'\, "' '? o - I I I ' I '-J-~,"-..,_ ,c"s..._...... / r J 'l .......,. o ,I\ \ .I'I") N t:,-~.,_~~! ~~.,,~ ,1"o-f ~\ - t . ;_,.- J '",L 1 - J ' I 0 r , o . \ 0 1.-,\ ____ I, . ' o,, "~ L~_ _. . .,\ l lb ' 0- . . ' __ ~-L ' ""~ ' - I1 0 Q 1' I / \ - ,"" C ,.)''- '' I1 I I ./'' ' \ ..... I ..'-~)..,f.,__.J~ I r' ., I --<''"-\_ \ '< - \ , -. , , , , I ~ _..._ ' ( ' '"'1 / . ,'\/, ;"~ _..J j - 0 18 _ ...r,_ l":,_,_._"t'\ ..., ..s . 'c:;,~ ' ,,' I I 'I"':.... ~ ' - -, ' ) ; "'t/ -~-~.--~~1r .;, ~', ,~~--.,. ~-:-~,.~4-'~' 0 ~ (' -~ ~ ~ '0 0 ~ ~ 'uo{ -- - 11 0. ., .., \_ /17 '' ' c.'--i]'~~~ . .J., ,../',_ ..,_I 0 c A "\ " I - ,_ - \. - - )- --.___,- - - < ' I \ l -0- I. c '\ ,...! " " t \. :.~r- , A S ..J 0 0:: ...: Ul PRP,1!.,.': 0 SHOR!!L 1!111'~ u, -----::--~~~~==========~1JL======~====~~====~~--~ c:: pre-4-o.t.-e Eorly Eocene ~ sea.Jev.J fall on.d eroalon Bi. . - - eeriY Eor~Eoc&M< fowltrBQ:oftd,rqiaaol uptift amt/or: levet-foll I ' 'I --r--;-:.....:...: __:_:__ f I 1 1 1 I 1 1 I A. LalrP......MIII~ CHidi E.an''' Eo....._, s-.11.-~r allllkSamiu trerr.e.-nlnr to eo fr.vf!l P-l'l'fJG I~ A I) I N t; ~~E~ N~~;~l~ ' - CI.INOHJI'II'IItl ', ' DIU!'0SITS S.CHEM~An~ l111A'GffAM-,S;AB:lNI AN CllEPOSlTI Q:N AnfT fEG,f.aNts:M:-GBlff&lA. cOASTAL PLAIN . EPOCH AGE z ~ :1i-(/) oL&J 0..~ oj! ~(I) (I) 0 0 GULF ~ OUTCROP COAST HATTAHOOCHEE STAGES VALLEY OUTCROP CENTRAL FALL LINE OUTCROP SAVANNAH VALLEY I SUBSURFACE SUBSURFACE SOUTHEASTERN SOUTHWESTERN COASTA L PLAIN COASTAL PLAIN THIS REPORT LATE "ACKSON IAN STAGE ., I ~ 1 -.l..J.-.L)-..l '? 1 ,_I . "w"' I c .!:! ..c J! 0 ID Q) c: c "1:1 cu :2 .c.. c ~ cu u :0e c 0 lU --c 0 :ll u ..J Lisbon "g CD -0 -...0:::: CD -Q) ....: '- a0.. 0:::: 0 "g > ~ ~ McBean Lisbon Lisbon 0 Q) "g 0:::: :I 'E.C.D. 00 0 iii ->...- 0 ... ....C..l..) 0:::: 0 "C 0:::: ...0:::: ~ "' 0 .D :::- Ql 0:::: 0 0 CD '0 0 .c X. E 0 ..J 0 Tollahatto Tallohotta Early ,c: E z ~ Q) a. z >- ID crCn SABINIAN STAGE Figure 18. Time-rock chart of the Claibornian Stage, Coastal Plain of Georgia. oooz- -144- ClAIBORNIAN STAGE ISOPACH MAP I ) thickness :J outcrop ro downthrown side of fault numbers in feet ..I.... "UI"1' 2> LOCAT10N MAP ..... t ,. 1 H Y Y 1 N Figure 20. I $ I ,_ -~ I I .. -VUioiV!_'t,. GfOotc;,AIQUT-ESTl-COI.LlGI [ l I . ~eN 1 l~t I 8tle8 H I <.: ~ ':&1-: :,"7 ~= II lirk.f cdls" OUTCROP P4ATT,lHCHEE II SINH VALLfi I OUTCROP OUTCROP FLINT R-IVER VJtt.LEY jocwLAGStT ORFt\IR S:uJ.-Ut.' s-su~FAci !8 I ftid~ ffl~ OLIGOCENE ~ ,.-,- I -.-1 -.--1 T"""""T" ,......,. I . . , - SERIES . :t. 0 d\ I .,I Gil L8/l I~rtB:;Ia~ I ;J~ilia!n of ~of9ia.~ I___,._ ..... \.!.-._ , --- --r , _,._~ ,or- \ ~~ ~ e .. , , . . . . ... _ ....1!4- _ \. t 1 .J " lo :y y Ul AID sp 7.! .1 1' I , , .. . .,.,. JACKSONIAN STAGE STRUCTURE-CONTOUR MAP - OF THE TOP ,.., 1 '- ~ N ' i I ( elevation related to sea level (sl) o outcrop ,. downthrown side of fault numbers in feet I ...I... ~ -...I I I B LOr.AllON MAP L j t ~ -~ ~ .: - -.1- ). , --r;: . I rI ----/ -,7~ ~ - !' ~ / '1 -~.- ..; m - .._ _ _ ~ I .J I 5 i- <11~ :~ \"; - ~ p -~,~.. -;. =. ~~ :..\ ____) . .... ) tt 8 .OS. ' "'S 'r'b L v~~ I .,.II? .., I " \ l \' _j I I \ ,...,..~.,.,., ,. ,.. o 1.0 I cG;J GJ 0' 0 GJ ac.. uaca.. -0 D 0 Early Rupelian '0 .0 :::J II) Suwannee Suwgnnee .?:- 1----r- r- r l . - r-r- 1--.-- r-r r-r- r-r 0 --E... 0 c0 : \ ~ \ Oligocene Series lzU ~ @ LATE I PR lA- JACK- SONIAN SONI AN Figure 24. Time-rock chart of the Oligocene Series, Coastal Plain of Georgia. i z -- - -!..j --i ,)- I /r--1 .. " II?,>, ~ ~ < I ~ ,. . / I iIII U') N (II 1-.l ::l ..0..'.1 I~ ~ I ' I c ( I 1 I ,.- ~ - ---i ,.._ .~ .J. , .; I ;''I t I ( ~.'l . - --J l - .... - ..,. "' -150- OLIGOCENE SERIES ISOPACH MAP thickness = outcrop o rocks not present <._ ...I... 10 downthrown side of fault numbers in feet ::_ -.~ - l\ .U...1.. " I \_ I I ,I 2) - lOCATION MAP --- -' - -- ... .,; ,' { ,-' \ ....,. ~ - "~ - t 1 n Ja tJ y Mil .. ~ ~ u ., y y y I J! t t r 1 N -tJq \ \ ~ l i:. ~ . "" Figure 26. COASTAL PLAIN ~ (NW) ..J ..J .....J lL OCMULGEE RIIIER GULF TROUGH OFFSHORE PRESENT SHOREL.INE w (58 ': g >-: "' JOIDS 0 I u ----=..._~~==-----r==:c:::=~ll ~~~ j frc~:::=J====-=~--=r--~,r ,"r F. Early Miocene 1 1 continued faulting, regional uplift, sea level fall, erosion E. late Late Oligocene and Early Miocene sea level r1se and transgression Lot~~? 0 . post-early Olig: : = ~ 1 1 l 1 = continued foul11ing, regional uplift, sea level fall, erosion 1 -= ~ C. early Late Oligocene sea level rise ~nd transgression B. post-Middle- :ligocen:TI f (~ ~-~- faulting, regional uplift and/or sea level fall,i!rosi on ... A. Early and Middl:e Oligocene sea level rise and transgression Late Eoc en e erosi on surfa ce SCHEMATIC DlAG'RAM-OLIGOCENE DEPOSITfON AND TECTONISM GEORGIA COASTAL PLA1N Fi.9ure 27 . -152- COSMOPOLITAN TERM I NO LOGY ERA PERIOD EPOCH STAGE NEOGENE zIIJ IIJ CHATTIAN 0 0 -(.) 0 N 0 z lu.LJ C) wzw ..J 0 <.!) IIJ 0 w Z IIJ 0 J 0 w N 0 (/) (.) .<,_I w 0:: l.LJ (.) TURONIAN CENOMANIAN ALBIAN :E APTIAN ~ lr <( IIJ NEOCOMIAN JURASSIC MILLIONS OF YEARS AGO GULF COAST TERMINOLOGY STAGE EPOCH PERIOD ERA 20 30 40 50 60 70 80 90 100 110 120 NEOGENE r-- 2 ILl NOT FORNALLY 0 0 SUBOIVIOEO ~ ..J 0 JACKSONIAN IzIJ ILl CLAIBORNIAN 0 0 wzw (!) -(.) 0 N w0 z0 UJ J 4 r--~ - CL l.LJ (J SABINIAN Ill 0 0 11.1 MIOWAYAI'i ..J < IL NAVARRO TAYLOR ... AUSTIN ..J ::::> C) en ::> 0 w -(.) 0 (.) .<,_I w N 0 (/) 0:: (.) w IIJ :E X 0 z <( ~ 0 u 130. JURASSIC 140 I Figure 28. Chart showing relationship of Gulf Coast stages, cosmopolitan stages, planktonic foraminifer zones, and sea-level changes according to Vail and others {1977). B .,....-,_..,..------... F ,~41 \ ..... ,..---_...-:. "------r\ l \ ' . ,.. I j \ ~'5/ \ .,..__..._1_.\ .,_..1_r_-__ \.\I D I, ( l ~''\ ....- ........... r---c""__,./.\l . A i . \ ,L ~ ' r;.-- - - ~ ' A.r-..-,..A.)...~~~I-r' y 110 2p 3p 4 0 sp Miler 1 I ' I I I I I I 0 10 20 30 40 50 60 70 BOKilometers A' r ,.~ l- -.~- ~"- ( '...__ 7,2 .!. V1 ~ I ~~ ~ (' I i ; r l. ("-._ - - -".T - -},'"-r--- J . ; ...... ~I' ~~-r--'II I ,. ! \ .: l ' \ '~ l '! l ,_ ' 1 - - .1"'-"LJ_ .i. . _ .\J..._ ,..,. .- - -.?'r:: \ I l i " r - - - ~ - - s~ ' \ D' ( , i .I - . .. - .)' Figure 29. Index map, cross sections A-F, Coastal Plain of Georgia. ,......... ............ ,., .,b A ....,~~,, t;.of' ,,. '!>,\,.~.t._,.'!>_o.<.'.._,\..)\",4'!>'0q' '!>" ,.'!> b'q I I-' U1 If LEGEND Nu N1agn uncliH11r1nliatd 0 Oligocn Sriu J Jackoonian Stag Cl Claibornian Srog1 S Sabinian Slog M. Mid .... ayan Stage TKu TlrliDr'J-CriiDCIOuo undifllrenliotd G Gulfion S1riu Co Comanchean S.ris I ....,.,.... , ~ -=----::1 l O M, f lo uu c.O"f>\~~('lo ' " Groundt:::~n t'"''"8 ~ ol .. aloaoal " ......... ..-~..-'1 -. ~~1 "\''o\''o' '' , 0 '!>,s '!>oo ,1 .so s's ,q1o ..,&'(\ tt-oft. 0t..o.ft.,...~.o<'\t: '\t""\\(' ,q ,,b '!>, ... 'fl...,c\ ft.\Jc\ ft.u' t;.(C\o \.(C\o'i:.(too ,, ... ..~,(\ )~ ,').... A' ~qO _,~.... ~ooo_ . I 0 'a Sota_ '}o L-1 ~ '""'-'- "'"'- "''--.., ' '""'- '""'-:- ,,.._ i 60001 Figure 30. (Refer to index map, Figure 29) D'l N a> 1-1 ~ ..Q...'l . ~ ...., ... ~ II Q. feU ""~::-. .... ~ >< .~.s.:.: .s ~o~ 1 .~ b0" 1 ' '~>'~-~ 0 ~,'1.,1..,.......,., . ~ ~ q'\'~> ,o1 , . . .c.''. . . qb '" ,..... ....c'\00 c0\\ p..\ . "' c - . -. .. -..~ .'.--~..f---,-., --r - .. ~1,.,. ,.. I , ;_, I ...,, .. I., " ,... 16' ,b.. ,.,o o' r IcO.I'\<''"U'cLS.'<''" "'"'o';,-,.o,, ooa., " ,..,_,. ._ .-;1 I __ , '' ,.. . r ------ ' ~~1~- ....__ . ~0~,1~ ;_[~;;{ .!.fi~]~.R..--,., l !~ l0 ~1~~f1, ]~~ ~:, 'in'~" 1!!!....~~--~,. III -t l'I<\=;"1j""'" I .:!]- ,'r I L. .;;!.; lM "'<-t1 I I III ~, ~I :; I I . I!I ;,!..~I1y~ ;,i = = f'"''\'-""'1, '! ~+ _.:._- ~' I ~ Figure 32. (Refer to index map, Figure 29) .... .. ~ t-.. ,o~r -, r t 1 - 1 J ~ i t r- f ~ -- -j 0..> ~ ____1~ I ,, I" J-~ ---~-- - I ~ ' , ~ I I ~: !- i i -1sa- -1 I ;u . ~ ~ ... -159- 0'1 N (!) 1-1 ::::1 0\ .-l .~ qo M Q) 0.. 1s0 1-1 ::::1 0\ .-l ~ X (!) 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Milton, Charles, and Hurst, V.J., 1965. Subsurface "basement" rocks of Georgia: Ga. Geol. Survey Bull. 76,56 p. Mitchum, R.M., Vail, P.R., and Thompson, s., III, 1977. The depositional sequence as a basic unit for stratigraphic analysis: Am. Assoc. Petroleum Gaolo.gists Mem. 26, p. 53-62 -172- Murray, G.E., 1955. Midway Stage, Sabine Stage, and Wilcox Group: Am. Assoc. Petroleum Geologists Bull., v. 39, p. 671-696 1961. Geology of the Atlantic and Gulf coastal provinces of North America: New York, Harpers, 692 p. Neathery, T.L., and Thomas, W.A., 1975. Pre-Mesozoic basement rocks of the Alabama Coastal Plain: Gulf Coast Assoc. Geol. Socs. Trans., v. 25, p. 86-99 Newkirk, T.F., 1971. Possible future petroleum potential of Jurassic, western Gulf basin, in Future petroleum provinces of the United States ... : Am. Assoc. Petroleum Geologists Mem. 15, vol. 1, p. 1851-1862 Ogren, D.E., 1970. Ostracoda from the Paleocene Clayton Formation, central Georgia: Ga. Acad. Sci. Bull. v. 28, p. 149-152 Owen, Vaux, Jr. 1963. Geology and ground-water resources of Mitchell County, Georgia: Ga. Geol. Survey Inf. Circ. 24, 40 p. Patterson, S.H., and Herrick, S.M., 1971. Chattahoochee anticline, Appalachicola Embayment, Gulf Trough and related structural features, southwestern Georgia Coastal Plain, fact or fiction? Ga. Geol. Survey Inf. Circ. 41, 16 p. -173- Peterson, R.A., Fillipone, W.R., and Coker, F.B., 19S5. The synthesis of seismograms from well log data. Geophysics v. 20, p. 516-538. Pickering, S.M., Jr., 1970. Stratigraphy, paleontology, and economic geology of portions of Perry and Cochran Quadrangles, Georgia: Ga. Geol. Survey Bull. 81, 67 p. Pickering, S.M., Jr., and others, 1976. Geologic map of Georgia: Atlanta, Ga. Geol. Survey, scale 1 inch to 500,000 inches. Pilger, R.H., Jr., 1978. A closed Gulf of Mexico, preAtlantic Ocean plate reconstruction and early rift history of the Gulf and North Atlanti~: Gulf Coast Assoc. Geol. Trans., v. 28, p. 385-393 Pressler, E.D., 1947. Geology and occurrence of oil in Florida: Am. Assoc. Petroleum Geologists Bull., v. 31, p. 1851-1862 Prettyman, T.M., and Cave, H.S., 1923. Petroleum and natural gas possibilities in Georgia: Ga. Geol. Survey Bull. 40, 167 p. Prowell, D.C., and O'Connor, B.J., 1978. Belair fault zone, evidence of Tertiary fault displacement in eastern Georgia: Geology, v. 6, p. 681-684 -174- Rainwater, E.H., 1960a. Paleocene of the Gulf Coastal Plain of the United States of America: Internatl. Geol. Cong. 21st, Rept. Sec. 5, p. 97-116 1960b. Stratigraphy and its role in the future exploration for oil and gas in the Gulf Coast: Gulf Coast Assoc. Geol. Socs. Trans., v. 10, p. 33-75 1964. Transgressions and regressions in the Gulf Coast Tertiary: Gulf Coast Assoc. Geol. Socs. Trans., v. 14, p. 217-230 1970. Regional stratigraphy and petroleum potential of the Gulf Coast Lower Cretaceous: Gulf Coast Assoc. Geol. Socs. Trans., v. 20, p. 145-157. Sarmiento. R., 1961. Geological factors influencing porosity e .stimates from velocity logs. Am. Assoc. Petroleum Geologists Bull., v. 45, p. 633-644 Schlee, Joh~ 1977. Stratigraphy and Tertiary development of the continental margin east of Florida: u.s. Geol. Prof. Paper 581 F, p. Fl-F25 Scientific Software Corp., 1975. Well logging manual: u.s. Dept. Commerce, Natl. Tech. Service, PB 247-641 -175- Scrudato, R.J., and Bond, T.A., l972a Cretaceous-Tertiary boundary of east-central Georgia and west-central South Carolina: Southeastern Geology, v. 14, p. 233-239 Sengbush, R.L. , Lawrence, P. L. , and HcDonal, F. J. , 196.1. Interpretation of synthetic seismograms: Geophysics, v. 26, p. 138-157 Sever, C.W., and Herrick, S.M., 1967. Tertiary stratigraphy and geohydrology in southwestern Georgia: U.S. Geol. Su~vey Prof. Paper 575B, p. B50-B53 Sheriff, R.E., 1976. Inferring stra,tigraphy from: se.smic data. Am. Assoc. Petroleum Geologists Bull. v. 60, p. 528-54-2 Shipley,, T.H., Buffler, R.T., and Watkins, J.S., 1978. Seismic s-tt~atigraphy and geologic history of Blake Plateau and adjacent western Atlantic c.ontinental margin: Am. Assoc. Petroleum Geologists Bull. v. 62 p. 792-812 Siple, G.E., 19'(1)7. Salt water encroachment of Tertiary limestones along coastal South Carolina, in Hydrology of fractured rocks, vol. 2: Internatl. Assoc. Sci. Hydrology Pub~ 94, p. 439-453 Sloss, L.L., 1963. Sequences in the cratonic interior of North America: Geol. Soc. America Bull., v. 74, p. ~n.-111 Steinkraus, W., 1978. Biostratigraphy:,. in Geolog.ical and: operational summary,, COST no. GE~li. well, Sou:th:eas:tt. Georgia Embayment area, South Kt1antic OCS -176- (R.V. Amato and J.W. Bebout, editors): u.s. Geol. Survey Open-File Rept. 76-668, p. 29-41 Stephenson, L.W., and others, 1942. Correlation of the outcropping Cretaceous formations of the Atlantic and Gulf Coastal Plain and Trans-Pecos Texas: Geol. Soc. America Bull., v. 53, p. 435-4A8 Taylor, P.T., Zietz, I., and Dennis, L.S., 1968. Geologic implications of aeromagnetic data for the eastern continental margin of the United States: Geophysics, v. 33, p. 755-780 Toulmin, L.D., 1955. Cenozoic geology of southeastern Alabama, Florida, and Georgia: Am. Assoc. Petroleum Geologists Bull., v. 39, p. 20,-235. 1977. Stratigraphic distribution of Paleocene and Eocene fossils in the eastern Gulf Coast region: Ala. Geol. Survey Mon. 13, 2 vols.; 602 p. and atlas Toulmin, L.D., and Lamoreaux, P.E., 1963. Strat~graphy along Chattahoochee River, connecting link between the Atlantic and Gulf Coastal Plains: Am. Assoc. Petroleum Geologists Bull., v. 47, p. 385-404 Tschudy, R.H., and Patterson, S.H., 1975. Palynological evidence for Late Cretaceous, Paleocene, and Early and Middle Eocene ages for strata in the kaolin belt, central ~177- Georgia: U.S. Geol. Survey Jour. Research, v.3, - p.','i3=7;..445 Uchupi, E., and Emery, K.O., 1967. Structure of continental margin off Atlantic coast of United States: ..Am. Assoc. Petroleum Geologists Bull., v. 51, p. 223-234 U.S. Geological Survey, 197 6. Preliminary summary of-_ the 1976-Atlantic Margin Coring Program of the u.-.s. Geol--pgd.eal Survey: u.s. Geol. Survey open file Rept. 76-844, 217 p. u.s. Geological Survey, and American Association of Petroleum Geologists, 1961. Tectonic map of the United=States: Washington, D.C., scale 1 inch ~ to. 2~500,000.inches Vail, P.R., ~1itchum, R.M., and Thompson, S., 3d, 1977. ~ Global cycles of relative changes of sea level, part- 4 ' ~of . Seismic- stratigraphy and global changes of sea level: Am. Assoc. Petroleum Geologists Mem. 26, p. 83..;...97 Vaughan, T.W., 1900. A Tertiary coral reef near Bainbridge, Georgia: Science, v. 12, p. 873..;,..875 1910. A contribution to the geologic history of the Floridian Plateau, in Papers from.the Tortugas Laboratory of the Carnegie Institution of Wash.ington, Vol. - 4: Carnegie Inst. Pub. 133, p. 99~185 Veatch, J.O., and .- Stephenson, L.W., 1911. Preliininary~report on the geology of the Coastal Plain of Georgia: Ga. Geol. Survey .- Bull.. 26, 466.p. Vernon, R-.o., 1951. Geology of Citrus and Levy Count,ies, -178-. Florida: Fla. Geol. Survey Bull. 33, 256 p. Voorheis, M.R., 1970. Paleontological evidence for Pliocene age of "high-level gravels", Taylor County, Georgia (abstract): Geol. Soc. America Abs. with Programs, v. 2, p. 246-247 Weaver, C.E., and Beck, K.C., 1977. Miocene of .the S.E. United States, a model for chemical sedimentation in a peri-marine environment: Sed. Geology, v. 17, p. 1-234 White, WalterS., 1965. Bauxite deposits of the Warm Springs district, Meriwether County, Georgia: U.S. Geol. Survey Bull. 1199-I p. Il - Il5 Winston, G.O., 1976a. Florida's Ocala uplift is not an uplift: Am. Assoc. Petroleum Geologists Bull., v. 60, p. 992-994 1976b. Subsurface geology of the Citrus, Levy, and west Marion County area, Florida, in Tertiary carbonates, Citrus, Levy, Marion Counties, west central Florida: Southeastern Geol. Soc. Guidebook 18, p. 36-48 Woollard, G.P., 1955. Preliminary report on seismic investigation in Tift and Atkinson Counties, Georgia: Ga. Mineral Newsletter, v. 8, p. 69-77 Woollard, G.P., Bonini, W.E., and Meyer, R.P., 1957. A siesmic refraction study of the sub-surface geology of the Atlantic Coastal Plain and continental shelf between -179- Virginia and Florida: Univ. Wisconsin, Dept. Geoloqy and Geophysics, 128 p. Z.app, A.D., 1965. Bauxite deposits of the Andersomril.l.e district, Georgia: U.S. Geol. Survey Bull. 1199G~ p. GL - G37 Zietz., I., 19,70. Eastern continental margin of the United States: Part 1, a magnetic study, in The Sea.. John Wi'ldy and Sons, New York. v. 4, pt. 2, p. 293-310 Zoback, M.D., and others, 1978. Normal faulting and in situ s:t.ress in the South Carolina Coastal PLain near Charleston: Geology, v. 6, p. 147-152 -180- Appendix 1. Sources of Information for this Report Bac:tn len Hlll JerrJen Ubb Blackley Braatley Jrya.n Sulloc.h. 3urke :lhoun Candler Charlto, GGS SO HI ...l6 L '"' lSU ISH 1716 1155 %164 58 lH 160 \132 U4:! U6l 1861 U7Z l0l7 1361 1115 U43 1160 Z039 ZD49 ZOIJ ZlO~ Zl67 7 357 195 971 1038 Guy, llu:ley C1ty nrJ. J Pelunttt.J 41nd wll',.thdonl, Bradley lio. 1 Cuh . . 1 lapt l tt !lome no. 1 Jun Oil Co., Dottr Lalfaon ftO , 1 Cna\\)', Wlllacooc.;hee nu. 1 Bishop, Httnry Crosby 1'\D. 1 Blthop, Henry Cook no . 1 l!ishop, Chunce Royal no. Bl5hop, Elijah YJd::e:s no. Bhhop, Tho111as O~~ovi.s no. 1 Gray A.lu Clty no. 1 Layneo-Atlantlc, Plt:gefald Clty no . Cuh~. W. 4 . rope .n o . 1 Blthop, Joe Phillips no. 1 Bishop, Clarence Smith no . 1 Jtshop, Clayt on NJnshe~t no. J Bishop, J. R. To111b1Hlln no . 1 Slthoo, A. L. Wuver no. 1 Ga . 08pt, Natur.a 1 A:uourcu Everett, Alapaha Clty no. l Nashvtlle Clty Bishop, J. till, "f~Cil1 no. 1 Jhhop. L. ~. S~arborouah no .. BlJhop, C. L. Cooper no. 1 llshop, R. L. Rlce no. 1 Bhhop, Howard Ray no . 1 Bhhop, D. H. N.tl1n no. 1 Blshop, Joe Lloyd no. 1 LaYnt"-,.\tlanr. L~, Cochun field no. LayneAtlanr.lc, Streltlun Copany no. 1 Layne,.\tLanr.lc, Co~hnn C\ty no. Trulu~k, Carl Fnnc:l1 no . 1 Trulu~lr.. Joe Cav~nauih no . 1 710 93ll 1192 Hubh 011 Co., W. F . Hwlh11n no. Nahunta Clr.y Southern, llobolr.en Cit1 no. 1 :S 11 ~84 .at.9 s:J UO 8.1.6 5111 192 U j 89.& !19i" 899 1005 138:" u.: so \Ul l065 81 HZ lSS !11 a5ui6 Ill =zo Ht l9Z HZ llO lll l!l UH tnter H~r:itotan, :-t. G. l.a~oson n.o. 1 (.ltt!eton, H. !L Carntt :'\0, 1 Hu,n.es, !. ~. llo'i'eu :~o . 1! Crar. Qult;:nn ".:lty Carr, !t. L.. Hlru no . 1 C.1r:-, !ssle 'h:Kno~n 1\0. 1 C&rr, 'torvn Cltr :Jnc:!ervood, \tor:u.n, Star C~urc:h. no. l Underwood, Criln no. 1 Ur.derowood, ',f. IL Hunter :t.o. l Unde:-~ooc:!, !iuata: 110 . 1 Un.ier,.oQd., ~. V. Sicholl no. 1 Uncferwood, J. E. O::~oper no, 1 anclervood, J. ~. 'iyson no . 1 Un.4t!''WOod, S. C. :ooper no, 1 8a.sh.!or, CeorJia Park Service, Fort :ofc:A:littrr Guy, Pu.broke Cit;' n.o. 1 Sapp , ll ic: l'u:lon.ci Hill ?ark Tur:t.er, D:-os Inn StltnnJ, Sutuboro airport no. % t.etne-,.\ela.ntlc:, ~evL!s s~~ool no. Cr&)l', Brookl~ Clt'l LayneAt~.J.r.!ic, ?orul Clty TuTner, Willi :lift Sr.\ith no. l L.arnAthlltic, Staeuboro :!ty Sene. U. s. Geol. .Survey 7os:: no. Three Cr eeks 011. Co. no. 3 VLr11ini~ .:il.l;lply, ~i.:!ville SchneAtl:~ntlc, i-r*-!r'!l Gin and Wrl!'hau,., no . 1 'iun Ot.l Co., R.. V . E\11!1 no. 1 Sun 011 Co., Will(luahby no. 1 Ander,on. Gre."\t ~orthern P.aper Co. no . 1 Bcho ls ISO Hunt: 011 Co., Super lor Plnr. rro.Juct' no . lSI liunt Hl Co., ~uprlo-r Pi.ne flrotlucts no . 1~6 ttunt Oil Co . , Superior Pine i'roducts no . 169 Hunt .:'lil Co., ~ upe-rl.,r Plne Products no . U9 Hu~bh Oil Co., hflntr and Lonadal no ~ 610 ZllO 600 6SO 310 1431 120 lOU 120 350 301 141 750 710 140 202 107 uos 500 us U4 1107 lllS l!ll 4SU 4088 4ll2 600 1901 1441 U!l 1605 U30 Hit l!IO 1110 600 6SO ..4HZ U09 160 ISS soo Z22 .6Z.Ss l'O 810 u31o0 161 702 200 1zs0o01 uo 491 110 500 161 lOI 1015. 200 230 110 U7 61!2 1117 U! 100 110 U70 nu IOJ 10 210 110 1141 !Oll ~]10 1021 1000 L031 971 1SZO " 460' 110 1016 ll'S lllO 7510 oul l9L6 5861 4062 ua: (Z) (l),(l) . (!),(61 ( Z) (I) (2) (ZJ (2) (2) ~g t2J ()) (l) ~cl~)l (Z) (2) (%) (2) (Z) (I), (2) ,(1), (6) CtJ, csJ. cJ, csJ, ce1 (1),(3),(1) (1). (l), (4). (!). (6) m:m:m:~:l (2) (1). (2). (5). (6) (I). (51. (61 (1){1) ,(6) (1). (!). (6) Bl:l!l :lll:l!l me. App.lln (10.60) (l) (1) (1) ,(21, (3). (4) ,(5). (6) f3) (l) (51 (l) (l) (JJ (l) (-l ) (l) (lf m(l) m(l) (%) (%) ( l) (l) (l) (l) (1), (!). (6) (2) (2). (l) (l) (2) (1). (2) '''.(I) ,(6) (1), (41 ,(S), (6) (Z) (2) (2) (I) m(l). (51, (6) (2) (2) (1). (2 ). (!), (6) (1),(Z), (I), (61 (1). (5) (2) (2) (Z) (Z) (l),(!J,('J,(Sl.(6) ((Z2)) (2) (Z), (I) (1), (Z), (S), (6) (1), (I), (6) (L), (!) {4). {5), (6) (4), {I), f6) (LJ, (41, (5), (6) (1),{4),(5),(6) OJ, {ZJ ,(4-J. rsJ. (6J -18'2- Appendix 1, page 3. arrlnchn Glynn Grady Houlton Irvin Jeff Oavh Jaf'hl"ton Laurens L. . Lowndes Nar Ion Me: tntuh Peach Plerce Pula'k1 lhndolph ...Ill Ul 569 17Z 116 372 373 567 568 5 20 l62 376 tin., Walter Stevens no. 1 ns HUt, Stth Moore no. u l4l0 aao (Z) (Z) (Z) (I) (Z) (2) (Z) (Z) (1), (2), (S), (6) (1) , (S), (6) liJO Yhalnla Machine Co., Tattnall State Prison no. Sll Turner, Troy Janie! no. 1 li"S huon and ..oh, Henry Spurlin no. 1 507 Gray, McRae City Zll LayneAtlantlc, 03-,UIOII Clty no. 3 lSO Layne~Atlantlc, Cir.H'~" S<:hoo1 no. o6 L~yne-Atlantic, Bron,..ood City no. SOl Gray, Co<:ke Flsh Hatc:huy no. 1 IZO 6H ooa 51S lOll 333 Sl SU7 (2) (2) (I) ,(2), (5), (6) (2) m (2) (Z) 19 132 <695 1156 9Z4 lll4 JlU Steven South.,n. U. S. Ar11y ahEleld no. LayneAtlantlc:, Tborusvllle Clty na. S Larne.\thntlc, Waurtr htroleu Co. no. 1 CarT, Ja11es Groover no, l Carr. 11. H. Pilc:l'ter no. t Durha, I. B. W, Sedawlck no. lA Cn, Netas Clty 300 lOlS 905 SlO 530 667Z UO (Z) (Z) (Z) Gelbua (19":81 Gelb.au (1971) (l) GeJ.bau. (U71) U t.ayne-AUantlc, An~uur and Co. no. 1 l!H St..,eu Southnn, TUt City SOl (Z) su (Z) 95 Tropac: Oil Co., Glb,on no. t 1, Tropic OU Co. II, ~: llrovn no. 1 ]IUO 1185 Hl:Hl:lH:!:l 117 Rou .nd Ray, Jae~ Fowler no. 1 7-JO hrnwell, Jut' Gillis no. 1 189 Mc.) ~1;, :~i' ~p..,r:; (2), ,.,nnc::k ~1901;: (J) Jo!rri.:k, Uf\::'ubi.~sh.aJ, on f11e ''~~\'1:!'1. GedriL" ;eol(li1~ :iut~ev, .\:li:"'t1; (J), .l.ppll:'l u ..! \ppt:.n :~lool); (i~, A;ljll~:"' ant! o'-j)ptl.n (1?6'"}; (6) ~.~rsall 1 (11'0); (:''1 Huzble 'Jll C:Orj). cor;nl ;tr"i"~ (l'JSIUS~; ,JU.plt .ud :ta..::ods on flh vi.t!\ Utoriil Ceo1'lalc. SU:'\'~'!, .l.tl&M.l; :JP, i:il:l'li f!e:-1.lt !\Ulb4r -184-